Y. Lucisano-valim - Academia.edu (original) (raw)

Papers by Y. Lucisano-valim

Clinical & Experimental Immunology, 2008

A systematic study has been carried out to investigate the role of immunoglobulin isotype, epitop... more A systematic study has been carried out to investigate the role of immunoglobulin isotype, epitope density, and antigen/antibody ratio on the capacity of immune complexes to activate the classical and alternative pathways of human complement and for the complexes subsequently to bind to erythrocyte C3b-C4b receptors (CR1). For this purpose, a series of chimaeric monoclonal anti-NIP antibodies was used, which all shared the same combining site but had different human constant domains. Antigen epitope density was varied by coupling different numbers of NIP hapten molecules to bovine serum albumin. All three parameters affect complement fixation. In general, complement activation is better in antibody excess and at equivalence than it is in antigen excess, and better at high epitope density than at low epitope density, although the effects are variable for different immunoglobulin isotypes and for the two pathways. It has been confirmed that IgGI and IgG3 are good activators of the classical pathway and are tolerant to variations in both epitope density and antigen/antibody ratio. IgG4 and IgA do not activate the classical pathway in any circumstances. IgG2 activates the classical pathway only at high epitope density and at equivalence or antibody excess. IgM activates the classical pathway well only at the higher epitope densities and at equivalence or antibody excess but, in addition, shows an interesting and unexpected prozone phenomenon where immune complex in antibody excess inhibits complement activation by the classical pathway. The results of the alternative pathway activation are strikingly different. IgA is by far the best activator of the alternative pathway and is relatively tolerant to epitope density and to antigen/antibody ratio. IgM, IgGI and IgG3 do not significantly activate the alternative pathway in any circumstances. IgG2 is the best IgG subclass for alternative pathway activation but requires high epitope density and equivalence or antibody excess. Binding to CR1 in general parallels the amount of complement fixed independent to the pathway by which it is fixed. However, IgG1 and IgG3 complexes in antigen excess activate complement well but bind poorly to CR 1. Nascently formed complexes seem to bind complement in a way that is similar to that bound by preformed complexes, but are then less able to bind to red cell CR 1. These observations help to explain the pathogenesis of complement activation in various autoimmune and immune complex diseases such as systemic lupus erythematosus, autoimmune thyroiditis and others. Keywords antibodies complement immune complexes immunoglobulin Recent evidence has suggested that, in the circulation, comple-Schifferli & Taylor, 1989). Studies performed in monkeys have ment and its receptor (CR1) on erythrocytes are involved in the shown that large preformed immune complexes (ICs) activate physiological processing and elimination of immune complexes complement in vivo, fix C3b and bind to red blood cells (RBC

Die Pharmazie, 2007

Atherosclerosis has been described as an inflammatory disease in which polymorphonuclear leukocyt... more Atherosclerosis has been described as an inflammatory disease in which polymorphonuclear leukocytes (PMNLs) seem to be involved. These cells may induce atherosclerotic lesions by releasing reactive oxygen species (ROS) and a sort of pro-inflammatory mediators. In this study, the PMNL oxidative metabolic status of Golden Syrian hamsters fed a normal diet (ND), or a high-fat diet (10% coconut oil plus 0.2% cholesterol) supplemented (R-HCD) or not (HCD) with 0.1% (w/w) rutin was evaluated after 120 days of treatment. PMNL oxidative metabolism was assessed by whole blood luminol-enhanced chemiluminescence and 2',7'-dichlorofluorescein diacetate-dependent flow cytometry. The results obtained by both methods were similar and showed no significant changes in ROS generation by PMNLs in blood samples from HCD or R-HCD animals when compared to ND. Furthermore it was shown that rutin supplementation did not significantly affect plasma lipid and lipoprotein levels in the hypercholestero...

Journal of Immunological Methods, 2014

In vitro assessment of the functional responses of leukocytes sometimes requires their isolation ... more In vitro assessment of the functional responses of leukocytes sometimes requires their isolation from blood, joint and tissues. In this study, we compared the efficiency of two procedures - the gelatin method and Ficoll-Hypaque density centrifugation gradient - to isolate peripheral blood neutrophils of healthy individuals and patients with active rheumatoid arthritis (RA). We also assessed whether these procedures affect the neutrophil activation status. Both purification procedures were concluded in 90min, and yielded cell populations with similar degrees of purity (80-90%), number of neutrophils (1-2×10(6) cells per mL of blood), and viability (97-100%). In vitro neutrophil priming with granulocyte-macrophage colony-stimulating factor (GM-CSF) significantly increased the reactive oxygen species producing ability of the cells stimulated with n-formyl-methionyl-leucyl-phenylalanine (n-fMLP), soluble immune complexes (s-ICs), and insoluble immune complexes (i-ICs). Isolated neutrophils not treated with GM-CSF responded to n-fMLP and i-IC, but not to s-IC. Almost all of the neutrophils (98-100%) purified by both methods expressed FcγRII/CD32 and FcγRIII/CD16, but they did not express significant levels of FcγRI/CD64. Similar results were obtained for healthy individuals' and RA patients' neutrophils. In summary, the gelatin method was comparable to Ficoll-Hypaque gradient in terms of purity, yield, and viability of the neutrophil preparations. Both methods neither primed or activated the neutrophils, nor affected their functional responsiveness. Therefore, both methods are suitable to isolate peripheral blood neutrophils of healthy individuals and RA patients.

Phytotherapy Research, 2004

Formation of circulating immune complexes (ICs) is essential for clearance of invading agents. In... more Formation of circulating immune complexes (ICs) is essential for clearance of invading agents. In some circumstances ICs might deposit on host tissues, leading to an inflammatory process that involves massive activation of neutrophils (PMNs), release of reactive oxygen species (ROS) and lysosomal enzymes and damage to the host tissue. Extracts of plants from Lychnophora sp. are used in Brazilian folk medicine as antiinflammatory agents. In this study, we evaluated the effect of eight flavonoids isolated from L. granmongolense, L. salicifolia and L. ericoides on the generation of ROS by rabbit PMNs stimulated with two kinds of ICs: particles of serum-opsonized zymosan (OZ) and insoluble ICs (ICIgG). ROS production was measured by chemiluminescence (CL) assay. We observed that 5- and 7- dihydroxylated compounds at 5 micromol/L inhibited almost totally ICIgG- and OZ-triggered luminol-CL and OZ-triggered lucigenin-CL. The degree of inhibitory effect among the other flavonoids was different, depending on the kind of ICs used to trigger ROS generation by PMNs and the number and position of methoxy groups. Moreover, under the conditions assessed, the studied flavonoids were not toxic to the rabbit PMNs. These results suggest that the actions of flavonoids on ROS generation by stimulated PMNs are highly dependent on their structures.

Phytotherapy Research, 2006

Excessive generation of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMNL) is i... more Excessive generation of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMNL) is involved in the pathology of many inflammatory diseases. Compounds isolated from natural sources with antioxidant activity can be helpful to inhibit and/or modulate the oxidative damage associated with PMNL-derived ROS. The present study investigated the relationship between the chemical structure of five methoxylated flavonoids, isolated from Chromolaena hirsuta and Chromolaena squalida, and their inhibitory activity on ROS generation by opsonized zymosan-stimulated PMNL. The antioxidant efficacy of the studied flavonoids, assessed by luminol-dependent chemiluminescence, was dependent on the position and number of methoxy and hydroxy groups.

The Journal of Rheumatology, 2014

Patients with systemic sclerosis (SSc) exhibit increased toxicity when exposed to genotoxic agent... more Patients with systemic sclerosis (SSc) exhibit increased toxicity when exposed to genotoxic agents. In our study, we evaluated DNA damage and polymorphic sites in 2 DNA repair genes (XRCC1 Arg399Gln and XRCC4 Ile401Thr) in patients with SSc. A total of 177 patients were studied for DNA repair gene polymorphisms. Fifty-six of them were also evaluated for DNA damage in peripheral blood cells using the comet assay. Compared to controls, the patients as a whole or stratified into major clinical variants (limited or diffuse skin involvement), irrespective of the underlying treatment schedule, exhibited increased DNA damage. XRCC1 (rs: 25487) and XRCC4 (rs: 28360135) allele and genotype frequencies observed in patients with SSc were not significantly different from those observed in controls; however, the XRCC1 Arg399Gln allele was associated with increased DNA damage only in healthy controls and the XRCC4 Ile401Thr allele was associated with increased DNA damage in both patients and controls. Further, the XRCC1 Arg399Gln allele was associated with the presence of antinuclear antibody and anticentromere antibody. No association was observed between these DNA repair gene polymorphic sites and clinical features of patients with SSc. These results corroborate the presence of genomic instability in SSc peripheral blood cells, as evaluated by increased DNA damage, and show that polymorphic sites of the XRCC1 and XRCC4 DNA repair genes may differentially influence DNA damage and the development of autoantibodies.

Inflammation Research, 2007

Objective: Eosinophils and cytokines are implicated in the pathogenesis of allergic diseases. In ... more Objective: Eosinophils and cytokines are implicated in the pathogenesis of allergic diseases. In the present study, we investigate the anti-infl ammatory effect of quercetin and isoquercitrin in a murine model of asthma. Methods: BALB/c mice were immunized (ovalbumin/aluminum hydroxide, s. c.), followed by two intranasal ovalbumin challenges. From day 18 to day 22 after the fi rst immunization, the mice received daily gavages of isoquercitrin (15 mg/ kg) or quercetin (10 mg/kg). Dexamethasone (1 mg/kg, s. c.) was administered as a positive control. Leucocytes were analyzed in bronchoalveolar lavage fl uid (BALF), blood and pulmonary parenchyma at 24 h after the last ovalbumin challenge. Interleukin-5 (IL-5) was analyzed in BALF and lung homogenates. Results: In animals receiving isoquercitrin or quercetin, eosinophil counts were lower in the BALF, blood and lung parenchyma. Neutrophil counts in blood and IL-5 levels in lung homogenate were lower only in isoquercitrin-treated mice. No alterations in mononuclear cell numbers were observed. Conclusion: Quercetin and isoquercitrin are effective eosinophilic infl ammation suppressors, suggesting a potential for treating allergies.

Immunological Investigations, 1999

This work investigated the correlation between serum levels of factor B, AP-lytic activity, ratio... more This work investigated the correlation between serum levels of factor B, AP-lytic activity, ratio of factor B activation by zymosan, and AP-dependent neutrophil phagocytosis in samples of normal human serum (NHS). In addition, since the antithyroid drug propylthiouracil (PTU) induces increased levels of AP lytic activity in rats, groups of these animals were treated with this drug in order to increase AP titers and to evaluate those parameters also in this condition. The results showed no correlation between factor B concentration and AP lytic activity in 18 samples of NHS or between factor B concentration and proportion of consumption by zymosan. Interestingly, this consumption was also not correlated with phagocytosis as measured by the chemiluminescence (CL) response of neutrophils to the opsonized particles. The two biological properties of phagocytosis and lytic activity, dependent of AP, were not correlated to each other in the NHS samples. In the samples of rat serum with increased AP lytic levels a different result was observed. A positive correlation between CL response and lytic activity occurred in serum of animals receiving a low PTU dose, but not in serum of animals receiving a high dose, where CL responses were lower than those of controls. The results are compared to literature data and discussed in terms of individual differences in resistance or susceptibility to infections and or diseases involving the complement system.

Cell Biochemistry and Function, 2005

Graves' disease shows important systemic inflammatory complications and has been consider... more Graves' disease shows important systemic inflammatory complications and has been considered to be systemic autoimmune thyroid, skeletal muscle and connective tissue syndrome. Neutrophils participate in the pathophysiology of the two major immune and inflammatory manifestations of the disease, ophthalmopathy and myxedema, and may worsen the inflammatory picture. In this study we analysed some biochemical and functional aspects of neutrophils in Graves' disease patients to assess their participation in these processes. The results show that the complement and/or Fcgamma receptor-mediated oxygen radical production by neutrophils was increased when patient cells were compared with controls. However the percentage of cells expressing complement and IgG receptors and the per-cell fluorescence, were similar, indicating that the increased oxidative burst was not due to an abnormal expression of mediating receptors. The production of hydrogen peroxide was also increased in hyperthyroid patient neutrophils as compared to controls. Conversely, antioxidant defences (superoxide dismutase activity and reduced glutathione content) in neutrophils from patients were not significantly different from healthy controls. The liberation of potent oxidative compounds together with the absence of adequate quenching of them by antioxidant mechanisms could be responsible for greater tissue damage in inflammatory conditions, as is the case in ophthalmopathy and myxedema patients. Considering our results and those of other workers, we encourage and suggest an associated antioxidant therapy to complement the conventional anti-thyroid therapy, especially in obvious inflammatory cases and in individuals who smoke.

$Research paper thumbnail of Salt fractionation of plasma proteins: A procedure to teach principles of protein chemistry$

Biochemistry and Molecular Biology Education, 2003

A two-step laboratory exercise in biochemistry is proposed, comprising salt fractionation of plas... more A two-step laboratory exercise in biochemistry is proposed, comprising salt fractionation of plasma proteins and protein quantification. This exercise targets mainly undergraduate students, namely in the second year of Pharmacy, who are up to this point more used to deal with physical and chemical properties of micromolecules than macromolecules. The exercise requires simple equipment usually available in basic laboratories. Students work in small teams or alone depending on the laboratory conditions. Questions are proposed to check and reinforce the essential concepts involved as a preparation for detailed comprehension of protein chemistry. After salt fractionation, protein samples can be stored before quantification, allowing a two-period schedule for the laboratory work. Exercises as proposed here are very useful to guide students to a detailed analysis of fundamental aspects determining structure and physicochemical properties of proteins.

Molecular Immunology, 1998