Benefits from dietary polyphenols for brain aging and Alzheimer's disease.

Brain aging and the most diffused neurodegenerative diseases of the elderly are characterized by oxidative damage, redox metals homeostasis impairment and inflammation. Food polyphenols can counteract these alterations in vitro and are therefore suggested to have potential anti-aging and brain-protective activities, as also indicated by the results of some epidemiological studies. Despite the huge and increasing amount of the in vitro studies trying to unravel the mechanisms of action of dietary polyphenols, the research in this field is still incomplete, and questions about bioavailability, biotransformation, synergism with other dietary factors, mechanisms of the antioxidant activity, risks inherent to their possible pro-oxidant activities are still unanswered. Most of all, the capacity of the majority of these compounds to cross the blood-brain barrier and reach brain is still unknown. This commentary discusses recent data on these aspects, particularly focusing on effects of curcumin, resveratrol and catechins on Alzheimer's disease.

Coxiella burnetii: the 'query' fever bacterium. A model of immune subversion by a strictly intracellular microorganism.

Although substantial progress occurred in the knowledge of Coxiella burnetii during the past years, the pathophysiology of Q fever is still obscure. Emerging evidence from clinical investigations suggested that certain disorders of cell-mediated immunity play a pivotal role in Q fever and especially in its chronic form. This review analyses the potential strategies that C. burnetii, a strictly intracellular pathogen, use to divert microbicidal mechanisms of macrophages and to depress protective T-cell mediated immunity. The role of monocytes in the induction of Q fever is specifically discussed.

Adhesion, phagocytosis and cell surface energy. The binding of fixed human erythrocytes to rat macrophages and polymethylpentene.

Fixed human erythrocytes were used as model particles for the study of adhesion and phagocytosis by rat peritoneal macrophages. Erythrocytes were fixed with various concentrations of glutaraldehyde or tannic acid, or were treated with neuraminidase. Adhesion and phagocytosis of these cells were measured. In addition, the surface energy of these erythrocytes and macrophages was estimated by the contact angle technique. Free energies of adhesion, based on the cell surface energies, were correlated with both adhesion and phagocytosis.

Oxidative metabolism of polymorphonuclear leukocytes: modulation by adhesive stimuli.

Different agents such as phorbol myristate acetate (PMA), N-formyl-methionyl-leucylphenylalanine (fMet-Leu-Phe), or opsonized zymosan induced an oxidative burst in rat peritoneal polymorphonuclear leukocytes (PMNs) elicited by casein. Plastic adhesion of PMNs down-regulated superoxide (O2) release stimulated by PMA or fMet-Leu-Phe but had no effect on zymosan-induced O2 generation, indicating that the O2 forming enzyme, the NADPH oxidase, was not affected by modulation and that a common step of the transductional events induced by PMA or fMet-Leu-Phe might be involved in this regulation. We demonstrated that a differential translocation of protein kinase C (PKC) was not responsible for that modulation. PMA-induced secretion of granule content (vitamin B12-binding protein) was not susceptible to modulation, suggesting that the transductional pathways leading to O2 generation and granule secretion are partly separated. The adhesion of PMNs to different substrates (glass, plastic, albumin-, laminin-, fibronectin-, poly-lysine-, or concanavalin A-coated plastic) down-regulated to different extent superoxide release. Whether the nature of the biochemical signal induced by the diverse adhesive stimuli or a physical parameter such as binding strength was involved in this differential behavior remains to be elucidated. Since adhesiveness was dependent on the state of the cytoskeleton and O2 inducers were reported to stimulate actin polymerization, we studied the F-actin content and distribution of PMNs by using the specific fluorescent probe NBD-phallacidin and an original methodology allowing a quantitative analysis of fluorescence on both adherent and suspended cells. PMA induced a polarization of F-actin on suspended PMNs but had no effect on the intracellular distribution of F-actin in adherent PMNs. Thus, we suggest that the adhesion of PMNs induced an immobilization of F-actin, possibly correlated to the down-regulation of one of the transductional pathways involved in the NADPH oxidase activation.

Self-limitation of the oxidative burst of rat polymorphonuclear leukocytes.

The oxidative response of rat polymorphonuclear leukocytes stimulated by phorbol myristate acetate and N-formyl-methionyl-leucyl-phenylalanine was studied. Ferricytochrome reduction and peroxidase-catalyzed decrease of scopoletin fluorescence were used to monitor O-2 and H2O2 release in the extracellular medium. Oxygen consumption was also measured in some experiments. Decrease of chlortetracyclin fluorescence after stimulation of dye-loaded cells was used to study an early step of cell stimulation. Finally, a possible relationship between cell responses and the medium redox potential was explored. Three major conclusions were obtained: Ferricytochrome reduction is dependent on the total cytochrome concentration, and a simple mathematical model allows a tentative estimate of total superoxide anion production by stimulated cells. Increasing cell concentration results in a decrease of individual cell response, and this may be accounted for by a direct inhibition of cell-released hydrogen peroxide on the reactivity of leukocytes. Further, H2O2 may be shown to inhibit an early step of cell response. The solution redox potential does not influence cell reactivity, since it may be dramatically decreased without inhibiting cell response.

Myotonic dystrophy: defective oxidative burst of polymorphonuclear leukocytes.

Because myotonic dystrophy (MD) is an autosomal dominant multisystemic disorder affecting plasma membrane, we have studied the oxidative burst of PMNs. The PMA and fMet-Leu-Phe-stimulated superoxide generation is defective in the patient group as compared to controls: the response is both delayed and low. The kinetic parameters of the NADPH oxidase complex are not affected. We have not found any abnormalities in the membrane potential changes. In addition, the cytosolic protein kinase C (PKC) activity of resting PMNs is similar in MD patients and controls, and the translocation of protein kinase C in response to PMA is not impaired. The decrease of the oxidative response of PMNs from MD patients may be related to an abnormality of the environment of the NADPH oxidase.

Legionella pneumophila inhibits superoxide generation in human monocytes via the down-modulation of alpha and beta protein kinase C isotypes.

Legionella pneumophila may subvert monocyte defenses by several mechanisms including the inhibition of phagosome-lysosome fusion or the impairment of oxidative metabolism. We have investigated the effect of L. pneumophila Knoxville 1, a virulent strain that does not inhibit phagosome-lysosome fusion, on the oxidative responsiveness of human monocytes. Infection of monocytes with L. pneumophila for 48 h resulted in marked inhibition of superoxide generation stimulated by phorbol myristate acetate (PMA) but not by zymosan, a particulate agonist. Evidence is provided that L. pneumophila interfered with the transductional pathway (i.e., protein kinase C, PKC) leading to activation of the NADPH oxidase in monocytes. The phosphorylation of 34-, 48-, 62-, 68-, and 80-kDa proteins stimulated by PMA was markedly inhibited in infected monocytes. In addition, the expression of both alpha and beta PKC isotypes was partially inhibited in infected monocytes. Taken together, our data suggest that the down-modulation of PKC isotypes plays a role in the inhibition of PMA-stimulated superoxide generation.

Phagocytic cell function in aged subjects.

In order to study the activity of phagocytic cells in normal and pathological aging, we compared normal young and aged subjects and patients with Alzheimer's (AD) or Parkinson's (PD) disease. Blood granulocytes and monocytes were separately assayed for ingestion of three different particle species (opsonized zymosan, immunoglobulin-coated sheep red cells (IgG-SRC) and glutaraldehyde-treated sheep red cells (G-SRC]. The superoxide anion production induced by these particles was also measured. All granulocyte responses to zymosan and IgG-SRC were depressed in the three aged groups as compared to young controls. Hence, only functions involving a specific receptor (Fc or C3b receptor) seemed affected. Monocyte activity was slightly decreased in the same groups. No difference was found between AD or PD patients and normal aged subjects. Hence the phagocytic and oxidative defects we found were a consequence of aging.

Primary structure of a cationic Cu,Zn superoxide dismutase. The sheep enzyme.

The complete amino acid sequence of Cu,Zn superoxide dismutase from sheep erythrocytes has been determined. The sequence is very similar to that of the bovine enzyme, having the same number of residues (151) and only two substitutions in the 'hypervariable' region (residues 17-30). The 5 overall substitutions confer a positive charge on the sheep enzyme at neutral pH (pI approximately equal to 8). This charge is localized outside the active site region. The catalytic efficiency of the sheep enzyme is 15% less than that of the cow enzyme, confirming the hypothesis that the enzyme activity is related to the concentration of positive surface charge near the active site channel.

Evaluation of intercellular adhesion with a very simple technique.

Rosetting techniques are widely used to quantify or purify various lymphocytic subpopulations; however, these techniques cannot discriminate between different receptors of similar specificities and different binding strengths, further, they do not provide any information concerning the molecular mechanisms involved in cell-cell adhesion. This paper describes a very simple technique of assaying rosette stability: cell suspensions are driven with known pressure through a calibrated needle with a syringe. Adhesion is quantified before and after this treatment. This procedure did not damage rat peritoneal cells used in a model system. Further, this method yielded fairly reproducible results and allowed a crude estimate of the force involved in the binding of glutaraldehyde-treated sheep red cells (GSRC) or immunoglobulin-coated sheep red cells (IGSRC) by rat macrophages (an average force of 0.8 x 10(-7) Newton was needed to separate 50% of bound IGSRC from macrophages). Binding and binding strength were found to be independent parameters. Last, this method possibly provided a way of separating two distinct subpopulations of rat macrophages. It is suggested that this technique might be routinely used to refine rosette studies.

Study of cell deformability by a simple method.

Cell deformability plays an important role in many immunological processes, such as phagocyte chemotaxis and endocytosis. The most widely used method of assay consists in aspirating cells into glass micropipettes and measuring the length of the protrusion induced by a given pressure, or the minimum pressure required to drive cells into the micropipette. This procedure requires specialized equipment and delicate manipulation. The present report describes a simpler procedure: cells are centrifuged in petri dishes floating on a water cushion, then fixed and coated with 0.8 micron diameter latex beads, which allows rapid and accurate determination of their height. This method is compared with the micropipette technique by studying lymphocyte and macrophage-like cell lines in physiological medium and in the presence of a divalent cation chelator or a microfilament inhibitor. In addition to simplicity, the main advantages of this technique are that (i) many cells may be examined within a reasonable period of time, which allows testing of heterogeneous cell populations, and (ii) unexpectedly, centrifugation was quite harmless under our experimental conditions, since it did not impair cell proliferative ability nor phagocytic ability. It is concluded that the method may be used in clinical laboratories to explore phagocyte dysfunctions, as well as in experimental studies.

A differential role for interleukin-6 and tumor necrosis factor-alpha in schizophrenia?

Pro-inflammatory cytokines are dysregulated in schizophrenia. To determine the nature of the so-called inflammatory syndrome in schizophrenia, we investigated the circulating levels of various cytokines (interleukin (IL)-1 beta, IL-6, tumor necrosis factor (TNF)alpha), their natural antagonist (IL1-ra, TNF-RI, TNF-RII) and leukocyte activation markers (the soluble receptor of interleukin-2, soluble CD14 and soluble CD23) in subjects with chronic schizophrenia (n = 18) and in normal controls (n = 21). The levels of IL-1 beta and its antagonist and the levels of leukocyte activation markers were not significantly differents between patients and controls. Circulating levels of TNF alpha were significantly (p < 0.05) higher in patients than in controls and did not result from variations of its antagonist levels. The significant (p < 0.05) increase in patient IL-6 was related specifically to clinical status, i.e. illness duration. These data suggest a specific cytokine-mediated syndrome in schizophrenia. We hypothesize that TNF alpha and IL-6 reflect the genetic background of disease suceptibility.

Differential binding of anions to the active site of Cu,Zn superoxide dismutase. A study of the Co,Zn enzyme derivative.

The reaction of N3- with Co,Zn superoxide dismutase, a good analogue of the native Cu,Zn enzyme, was studied in the presence and absence of phosphate, which is known to perturb the spectroscopic properties of the cobalt chromophore in the Co,Zn enzyme. EPR, NMR, and optical titrations demonstrated the formation of different adducts for N3- depending on the presence of phosphate, at variance with results previously obtained with CN- [3]. This evidence indicates that the mechanism of anion binding to Cu,Zn superoxide dismutase cannot be described on the basis of data obtained with a single type of anions.

Adenosine and hemodialysis in humans.

BACKGROUND: Infections and hypotension are serious complications that develop during hemodialysis (HD) treatment. Adenosine (ADO), a strong hypotensive and immunosuppressive agent, may participate in these two HD complications, because high concentrations of ADO metabolites are found in dialyzed human plasma. ADO, which is released by endothelial cells, is quickly transformed into inosine (INO) by plasmatic ADO deaminase (ADA) and mononuclear cell ADO deaminase (MCADA). In plasma, the degradation of ADO into INO and its uptake by red blood cells (RBC) are both very rapid, resulting in the short half-life of ADO in blood. METHODS: Using liquid chromatography, we evaluated ADO and INO plasma concentrations before and after HD session. RESULTS: Before the HD session, ADO and INO plasma concentrations were higher in hemodialyzed patients than in controls and in peritoneally dialyzed patients. At the end of the HD session, ADO plasma concentration was increased. ADO plasma concentration for the undialyzed patients was in the same range as that of the controls. Before HD, ADA activity was higher in hemodialyzed patients (559 +/- 349 IU) than in controls (219 +/- 48 IU), and the activity rose during the session (665 +/- 135 IU). ADA activity in the undialyzed patients (222 +/- 80 IU) was in the same range as that of the controls (219 +/- 48 IU). Before the HD session, the MCADA activity (247 +/- 144 IU) was lower than in controls (624 +/- 99 IU). HD did not modify ADO RBC uptake. ADO inhibited mononuclear cell proliferation and interferon-gamma production in humans. Finally, as much as 50 microM INO does not inhibit ADO uptake by RBC and does not modify ADA and MCADA activities. CONCLUSIONS: These data indicate that chronic HD inhibited MCADA activity and increased ADO plasma concentration. Both high ADO plasma concentration and low MCADA activity may be involved in dialysis-induced immune system failure and thereby favor infectious diseases.

Characterization of Cu,Zn superoxide dismutase from the bathophile fish, Lampanyctus crocodilus.

Cu,Zn SOD from the bathophile teleost Lampanyctus crocodilus (LSOD) shows a high degree of homology with the sequence of the enzymes from other teleostean fish species. The catalytic properties of LSOD are very similar to those of the bovine enzyme, albeit with higher sensitivity to thermal denaturation. The apparent molecular mass of LSOD (37.6 KDa) is higher than the other Cu,Zn SOD variants studied. The aminoacid sequence of LSOD reveals interesting substitutions compared to the bovine enzyme. These are discussed in view of the particular environmental conditions to which L. crocodilus is adapted.

Monocytes and granulocytes in rheumatoid arthritis (RA): phagocytic activity and superoxide anion production.

It is suggested by many tests that phagocytic cells were implied in inflammation which occurred during rheumatoid arthritis (RA). Further, three subject populations were selected for this study: Rheumatoid arthritis patients diagnosed according to American Rheumatism Association criteria (ARA mean = 6) and treated with gold compounds. Control subjects treated with the same non-steroidal anti-inflammatory drug (NSAID), diclofenac (75 mg per day). Normal subjects without disease or treatment. Blood granulocytes and monocytes were separately tested for ingestion of three different particle species (opsonized zymosan, immunoglobulin G sheep red cells, glutaraldehyde-treated sheep red cells) and stimulation of superoxide anion production by these particles. All phagocytic cells in RA patients have normal phagocytic response and superoxide anion production. Autologous serum does not inhibit the activity of these cells. In addition the NSAID (diclofenac) does not act upon phagocytosis and oxidative burst of control cells.

Anti-neutrophil cytoplasmic antibodies (ANCA) and infection.

As ANCA are occasionally noted in patients with infectious disorders independently of any vasculitis process, we examined serum from patients with acute infection (n = 22) and septic shock (n = 57). Only two patients with acute infection were ANCA positive as determined by indirect immunofluorescence and western blot analysis. The clinical recovery of both patients was associated with negative immunofluorescence and western blot tests.

Mechanisms of leukocyte adhesion.

The interaction between granulocytes and endothelial walls may be influenced by the blood flow. This possibility was investigated by studying the influence of fluid flow on the adhesion and detachment of 51Cr-labeled rat granulocytes interacting with protein-coated glass surfaces. It is concluded that: i) Adhesion is markedly decreased when the wall shear rate becomes higher than about 20 s-1. ii) Pretreating glass with concanavalin A or polylysine significantly decreased adhesion, whereas fibronectin had little effect on binding. iii) Very high flow rates (about one thousandfold higher than those compatible with bond formation) were required to provoke substantial detachment of substrate-bound cells. iv) Coating glass with laminin or polylysine decreased binding strength whereas fibronectin or concanavalin A did not substantially influence this parameter. v) Exposing granulocytes to phorbol myristate acetate might increase the cell ability to form strong adhesions, whereas labile adhesion was unaffected or even decreased by this treatment.

A biological role for haemagglutination activity of Leishmania promastigotes and amastigotes.

Leishmania promastigotes and axenic amastigotes possess a haemagglutination activity (HA). Leishmania attachment to human macrophages was studied after a 30 min incubation in the presence of 10 mM carbohydrates at 37 degrees C. Galactosamine, sialic acid, heparin, mannose, and NAc-mannosamine impaired the attachment of promastigotes and amastigotes to monocyte-derived macrophages and the myelomonocytic cell line THP 1 whereas other carbohydrates had no effect. Preincubation experiments showed that mannose inhibits the macrophage receptor, whereas galactosamine acts on promastigotes. Moreover, the HA is considerably decreased after incubation with macrophages. Our results suggest that promastigotes of different Leishmania species and axenic amastigotes possess a lectin-like receptor with similar specificity, which is in some way involved in the attachment to vertebrate host cells.