Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
Mais filtros










Intervalo de ano de publicação
2.
Mol Immunol ; 116: 80-89, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31630079

RESUMO

Here we report the effects of exogenous and endogenous galectin-1 (Gal-1) in modulating the functional responses of human and murine neutrophils at different stages of activation, i.e. naive, primed, and activated. Exposure to Gal-1 did not induce ROS production in either naive or N-formyl-methionyl-leucyl-phenylalanine-primed (fMLP; 10-9 M) neutrophils. However, Gal-1 elicited a concentration-dependent ROS production in neutrophils activated with fMLP at concentrations ranging from 10-8 M to 10-6 M. Additional fMLP (10-7 M) stimulation of fMLP-activated neutrophils increased ROS production, whose intensity was inversely related to the fMLP concentration used in the first activation step (10-8 M to 10-6 M), and was not influenced by the presence of Gal-1. Naive neutrophils treated with Gal-1 and then exposed to fMLP (10-6 M) or phorbol-12-myristate-13-acetate (10-7 M) produced less ROS, as compared to naive neutrophils not treated with Gal-1. Interestingly, these in vitro Gal-1 effects were associated with Gal-1 carbohydrate-binding activity and the ability to decrease FPR-1 (formyl peptide receptor 1) expression in naive human neutrophils. Conversely, positive ROS modulation by Gal-1 in activated neutrophils was not associated with FPR-1 expression but it was related to its carbohydrate recognition. In vitro, fMLP stimulation of Gal-1-/- mouse neutrophils produced more ROS than fMLP stimulation of Gal-1+/+ neutrophils and this effect may be associated with increased FPR-1 expression. Exogenous Gal-1 induced ROS production in Gal-1-/- mouse neutrophils more effectively than in Gal-1+/+ mouse neutrophils. Compared to Gal-1+/+ mice, Gal-1-/- mice exhibited lower bacterial load in the peritoneal fluid and peripheral blood, thus indicating a greater bactericidal activity in vivo. These findings demonstrate that endogenous Gal-1 restricts ROS generation that correlates with bacterial killing capacity in inflammatory neutrophils. Thus, endogenous and exogenous Gal-1 may either positively or negatively modulate the effector functions of neutrophils according to the cell activation stage.


Assuntos
Galectina 1/farmacologia , Neutrófilos/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Adulto , Animais , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , N-Formilmetionina Leucil-Fenilalanina/farmacologia , Ativação de Neutrófilo/efeitos dos fármacos , Receptores de Formil Peptídeo/metabolismo , Adulto Jovem
3.
Rheumatol Int ; 38(6): 1043-1052, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29464314

RESUMO

We examined the functional activity of peripheral blood neutrophils and the complement system activation status in patients with rheumatoid arthritis (RA) undergoing infliximab/methotrexate combined therapy. We studied female RA patients under treatment with infliximab (3-5 mg/kg) and methotrexate (15-25 mg/week) who presented inactive (i-RA; n = 34, DAS-28 ≤ 2.6) or at least moderately active disease (a-RA; n = 29, DAS-28 > 3.2), and age-matched healthy women (n = 38). We measured the levels of reactive oxygen species (ROS) generation (chemiluminescence assay) and membrane expression of FcγRIIa/CD32, FcγRIIIb/CD16, CR1/CD35, and CR3/CD11b receptors (ELISA assay) in neutrophils. We also determined the hemolytic activity of the alternative and classical pathways of the complement system (spectrophotometry), serum levels of C5a and Bb (ELISA assay), and serum chemotactic activity (Boyden chamber). Compared with the control group, i-RA and a-RA patients exhibited: (1) increased neutrophil ROS production and membrane expression of FcγRIIa/CD32, FcγRIIIb/CD16, and CR1/CD35, indicating neutrophil activation; and (2) increased serum chemotactic activity and decreased activity of the alternative complement pathway, indicating systemic complement system activation. The levels of C-reactive protein in a-RA patients were augmented, compared with i-RA patients. Although infliximab/methotrexate combined therapy induced disease remission according to the DAS-28 criteria, both i-RA and a-RA patients still exhibited significant levels of systemic activation of neutrophils and the complement system.


Assuntos
Artrite Reumatoide/imunologia , Ativação do Complemento , Neutrófilos/imunologia , Adulto , Anticorpos Monoclonais/uso terapêutico , Complexo Antígeno-Anticorpo/biossíntese , Antirreumáticos/uso terapêutico , Artrite Reumatoide/tratamento farmacológico , Brasil , Feminino , Humanos , Infliximab/uso terapêutico , Metotrexato/uso terapêutico , Pessoa de Meia-Idade , Espécies Reativas de Oxigênio/imunologia , Espécies Reativas de Oxigênio/metabolismo
4.
Free Radic Biol Med ; 115: 421-435, 2018 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-29248721

RESUMO

In this study, we report the ability of a set of eight 3-phenylcoumarin derivatives bearing 6,7- or 5,7-dihydroxyl groups, free or acetylated, bound to the benzopyrone moiety, to modulate the effector functions of human neutrophils. In general, (i) 6,7-disubstituted compounds (5, 6, 19, 20) downmodulated the Fcγ receptor-mediated neutrophil oxidative metabolism more strongly than 5,7-disubstituted compounds (21, 22, 23, 24), and (ii) hydroxylated compounds (5, 19, 21, 23) downmodulated this neutrophil function more effectively than their acetylated counterparts (6, 20, 22, 24, respectively). Compounds 5 (6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin) and 19 (6,7-dihydroxy-3-[3',4'-dihydroxyphenyl]-coumarin) effectively downmodulated the neutrophil oxidative metabolism elicited via Fcγ and/or complement receptors. Compound 5 also downmodulated the immune complex-stimulated phagocytosis, degranulation of elastase, and production and release of neutrophil extracellular traps, as well as the human neutrophil chemotaxis towards n-formyl-methionyl-leucyl-phenylalanine, without altering the expression level of formyl peptide receptor type 1. Both compounds 5 and 19 did not impair the neutrophil capacity to recognize and kill Candida albicans. Docking calculations revealed that compounds 5 and 19 directly interacted with three catalytic residues - Gln-91, His-95, and Arg-239 - inside the myeloperoxidase active site. Together, these findings indicate that (i) inhibition of reactive oxygen species generation and degranulation of elastase are closely associated with downmodulation of release of neutrophil extracellular traps; and (ii) compound 5 can be a prototype for the development of novel immunomodulating drugs to treat immune complex-mediated inflammatory diseases.


Assuntos
Anti-Inflamatórios/farmacologia , Cumarínicos/farmacologia , Armadilhas Extracelulares/metabolismo , Neutrófilos/fisiologia , Elastase Pancreática/metabolismo , Receptores de Complemento/metabolismo , Receptores de IgG/metabolismo , Anti-Inflamatórios/química , Células Cultivadas , Cumarínicos/química , Humanos , Imunomodulação , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Peroxidase/metabolismo , Fagocitose , Espécies Reativas de Oxigênio/metabolismo
5.
J Pharm Pharmacol ; 69(12): 1829-1845, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28994118

RESUMO

OBJECTIVES: To examine whether the hydroalcoholic extract from Baccharis dracunculifolia leaves (BdE) modulates the human neutrophil oxidative metabolism, degranulation, phagocytosis and microbial killing capacity. METHODS: In-vitro assays based on chemiluminescence, spectrophotometry, flow cytometry and polarimetry were used, as well as docking calculations. KEY FINDINGS: At concentrations that effectively suppressed the neutrophil oxidative metabolism elicited by soluble and particulate stimuli (<10 µg/ml), without clear signs of cytotoxicity, BdE (1) inhibited NADPH oxidase and myeloperoxidase activity; (2) scavenged H2 O2 and HOCl; (3) weakly inhibited phagocytosis; and (4) did not affect neutrophil degranulation and microbial killing capacity, the expression levels of TLR2, TLR4, FcγRIIa, FcγRIIIb and CR3 and the activity of elastase and lysozyme. Caffeic acid, one of the major B. dracunculifolia secondary metabolites, did not inhibit phagocytosis but interfered in the myeloperoxidase-H2 O2 -HOCl system by scavenging H2 O2 and HOCl, and interacting with the catalytic residues His-95, Arg-239 and Gln-91. CONCLUSIONS: BdE selectively modulates the effector functions of human neutrophils, inhibits the activity of key enzymes and scavenges physiological oxidant species. Caffeic acid contributes to lower the levels of oxidant species. Our findings help to unravel the mechanisms by which these natural products exert immunomodulatory action towards neutrophils.


Assuntos
Baccharis/química , Fatores Imunológicos/farmacologia , Neutrófilos/efeitos dos fármacos , Extratos Vegetais/farmacologia , Adulto , Ácidos Cafeicos/isolamento & purificação , Ácidos Cafeicos/farmacologia , Citometria de Fluxo , Sequestradores de Radicais Livres/isolamento & purificação , Sequestradores de Radicais Livres/farmacologia , Humanos , Fatores Imunológicos/isolamento & purificação , Luminescência , Neutrófilos/metabolismo , Fagocitose/efeitos dos fármacos , Folhas de Planta , Espectrofotometria
6.
Artigo em Inglês | MEDLINE | ID: mdl-26273286

RESUMO

BACKGROUND: The skin secretions of toads of the family Bufonidae contain biogenic amines, alkaloids, steroids (bufotoxins), bufodienolides (bufogenin), peptides and proteins. The poison of Rhinella schneideri, formerly classified as Bufo paracnemis, presents components that act on different biological systems, including the complement system. The aim of this study was to isolate and examine the activity of Rhinella schneideri poison (RsP) components on the complement system. METHODS: The components active on the complement system were purified in three chromatographic steps, using a combination of cation-exchange, anion-exchange and gel filtration chromatography. The resulting fractions were analyzed by SDS-PAGE and screened for their activity in the hemolytic assay of the classical/lectin complement pathways. Fractions active on the complement system were also assessed for their ability to generate C3 fragments evaluated by two dimensional immunoelectrophoresis assay, C3a and C5a by neutrophil chemotaxis assay and SC5b-9 complex by ELISA assay. RESULTS: The fractionation protocol was able to isolate the component S5 from the RsP, as demonstrated by SDS-PAGE and the RP-FPLC profile. S5 is a protein of about 6000 Da, while S2 presents components of higher molecular mass (40,000 to 50,000 Da). Fractions S2 and S5 attenuated the hemolytic activity of the classical/lectin pathways after preincubation with normal human serum. Both components stimulated complement-dependent neutrophil chemotaxis and the production of C3 fragments, as shown by two-dimensional immunoelectrophoresis. S2 showed a higher capacity to generate the SC5b - 9 complex than the other fractions. This action was observed after the exposure of normal human serum to the fractions. CONCLUSIONS: This is the first study to examine the activity of RsP components on the complement system. Fractions S2 and S5 reduced the complement hemolytic activity, stimulated complement-dependent neutrophil chemotaxis and stimulated the production of C3 fragments, indicating that they were able to activate the complement cascade. Furthermore, fraction S2 was also able to generate the SC5b-9 complex. These components may be useful tools for studying dysfunction of the complement cascade.

7.
Artigo em Inglês | MEDLINE | ID: mdl-25450839

RESUMO

INTRODUCTION: This study aims to optimize some experimental conditions of a flow cytometric assay to examine the human neutrophil ability to phagocytose immune complexes (ICs) via Fcγ and complement receptors (FcγR and CR, respectively). The parameters assessed were: number of cells, concentration of ICs, reaction time, pH and concentration of the Trypan Blue quenching solution. METHODS: Neutrophils were isolated from peripheral blood of healthy volunteers. Precipitated ICs composed of IgG and fluorescein isothiocyanate (FITC)-labeled ovalbumin, opsonized or not with serum complement, were used to trigger the neutrophil phagocytosis via FcγR, CR, and FcγR+CR. Fluorescence of the internalized ICs was measured by flow cytometry, after quenching the extracellular fluorescence with Trypan Blue. RESULTS: The optimal experimental conditions established for the phagocytosis assay were: 1 × 10(6) cells mL(-1) and 40 µg mL(-1) FITC-labeled ICs, incubated for 30 min, at 37°C, in 0.5 mL of reaction volume. Trypan Blue solution at 1.25 mg mL(-1) pH4.4 was the best fluorescence quencher of FITC-labeled ICs attached to the outer surface of neutrophils. DISCUSSION: The selected experimental conditions were viable to evaluate IC phagocytosis by neutrophils; they are also suitable to compare the efficiency of IC phagocytosis mediated by FcγR and CR classes of membrane receptors, alone or in combination. This method finds application in studies of (i) the receptor-specific phagocytic function of normal and pathogenic neutrophils as well as (ii) the impact of drugs and therapies on this essential effector function of neutrophils.


Assuntos
Complexo Antígeno-Anticorpo/fisiologia , Neutrófilos/fisiologia , Fagocitose/fisiologia , Receptores de Complemento/fisiologia , Receptores de IgG/fisiologia , Células Cultivadas , Citometria de Fluxo , Humanos , Espécies Reativas de Oxigênio
8.
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-954750

RESUMO

Background The skin secretions of toads of the family Bufonidae contain biogenic amines, alkaloids, steroids (bufotoxins), bufodienolides (bufogenin), peptides and proteins. The poison of Rhinella schneideri, formerly classified as Bufo paracnemis, presents components that act on different biological systems, including the complement system. The aim of this study was to isolate and examine the activity ofRhinella schneideri poison (RsP) components on the complement system.Methods The components active on the complement system were purified in three chromatographic steps, using a combination of cation-exchange, anion-exchange and gel filtration chromatography. The resulting fractions were analyzed by SDS-PAGE and screened for their activity in the hemolytic assay of the classical/lectin complement pathways. Fractions active on the complement system were also assessed for their ability to generate C3 fragments evaluated by two dimensional immunoelectrophoresis assay, C3a and C5a by neutrophil chemotaxis assay and SC5b-9 complex by ELISA assay.Results The fractionation protocol was able to isolate the component S5 from theRsP, as demonstrated by SDS-PAGE and the RP-FPLC profile. S5 is a protein of about 6000 Da, while S2 presents components of higher molecular mass (40,000 to 50,000 Da). Fractions S2 and S5 attenuated the hemolytic activity of the classical/lectin pathways after preincubation with normal human serum. Both components stimulated complement-dependent neutrophil chemotaxis and the production of C3 fragments, as shown by two-dimensional immunoelectrophoresis. S2 showed a higher capacity to generate the SC5b- 9 complex than the other fractions. This action was observed after the exposure of normal human serum to the fractions.Conclusions This is the first study to examine the activity of RsP components on the complement system. Fractions S2 and S5 reduced the complement hemolytic activity, stimulated complement-dependent neutrophil chemotaxis and stimulated the production of C3 fragments, indicating that they were able to activate the complement cascade. Furthermore, fraction S2 was also able to generate the SC5b-9 complex. These components may be useful tools for studying dysfunction of the complement cascade.

9.
Z Naturforsch C J Biosci ; 69(7-8): 346-56, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25265855

RESUMO

Stimulated human neutrophils exhibit increased net oxygen consumption (NOC) due to the conversion of O2 into the superoxide anion by the NADPH oxidase enzymatic complex during the respiratory burst. In several inflammatory diseases, overproduction of these oxidants causes tissue damage. The present study aims to: (a) optimize the experimental conditions used to measure the NOC in serum-opsonized zymosan (OZ)- and insoluble immune complex (i-IC)-stimulated human and rabbit neutrophils; and (b) compare the effect of four flavonols (quercetin, myricetin, kaempferol, and galangin) on this activity. We used a Clark-type oxygen electrode to measure the NOC of stimulated neutrophils. Eliciting the neutrophil respiratory burst with OZ and i-IC yielded similar maximum O2 uptake levels within the same species, but the human neutrophil NOC was almost four times higher than the rabbit neutrophil NOC. The optimal experimental conditions established for both cell types were 4 x 10(6) neutrophils mL(-1), 2 mg mL(-1) OZ, and 240 microg mL(-1) i-IC. Upon stimulation with OZ or i-IC, the tested flavonols reduced the human and rabbit neutrophil NOC in the same order of potency--quercetin and galangin were the most and the least potent, respectively. These compounds were around four times more effective in inhibiting the rabbit as compared to the human neutrophil NOC, respectively. The four flavonols were not toxic to human or rabbit neutrophils. The experimental conditions used are suitable for both the determination of human and rabbit neutrophil NOC and for the assessment of the modulatory effects of natural compounds on these activities. The relationship between the level of NOC and the inhibitory potency of the flavonols suggests that rabbit neutrophils can be useful experimental models to predict the effect of drugs on immune complex-stimulated human neutrophils.


Assuntos
Complexo Antígeno-Anticorpo/imunologia , Flavonóis/farmacologia , Neutrófilos/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Animais , Humanos , Neutrófilos/imunologia , Neutrófilos/metabolismo , Coelhos
10.
Int Immunopharmacol ; 21(1): 102-11, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24797916

RESUMO

Rheumatoid arthritis (RA) patients usually exhibit immune complex (IC) deposition and increased neutrophil activation in the joint. In this study, we assessed how four flavonols (galangin, kaempferol, quercetin, and myricetin) modulate the effector functions of healthy individuals' and active RA patients' IC-stimulated neutrophils. We measured superoxide anion and total reactive oxygen species production using lucigenin (CL-luc)- and luminol (CL-lum)-enhanced chemiluminescence assays, respectively. Galangin, kaempferol, and quercetin inhibited CL-lum to the same degree (mean IC50=2.5 µM). At 2.5 µM, quercetin and galangin suppressed nearly 65% CL-lum of active RA patients' neutrophils. Quercetin inhibited CL-luc the most effectively (IC50=1.71±0.36 µM). The four flavonols diminished myeloperoxidase activity, but they did not decrease NADPH oxidase activity, phagocytosis, microbial killing, or cell viability of neutrophils. The ability of the flavonols to scavenge hypochlorous acid and chloramines, but not H2O2, depended on the hydroxylation degree of the flavonol B-ring. Therefore, at physiologically relevant concentrations, the flavonols partially inhibited the oxidative metabolism of IC-stimulated neutrophils without affecting the other investigated effector functions. Using these compounds to modulate IC-mediated neutrophil activation is a promising safe therapeutic strategy to control inflammation in active RA patients.


Assuntos
Anti-Inflamatórios/farmacologia , Artrite Reumatoide/tratamento farmacológico , Flavonoides/farmacologia , Quempferóis/farmacologia , Neutrófilos/efeitos dos fármacos , Quercetina/farmacologia , Adulto , Anti-Inflamatórios/química , Complexo Antígeno-Anticorpo/imunologia , Degranulação Celular/efeitos dos fármacos , Células Cultivadas , Feminino , Flavonoides/química , Humanos , Quempferóis/química , Pessoa de Meia-Idade , Neutrófilos/imunologia , Oxirredução/efeitos dos fármacos , Peroxidase/metabolismo , Quercetina/química , Espécies Reativas de Oxigênio/metabolismo , Relação Estrutura-Atividade
11.
J Ethnopharmacol ; 150(2): 655-64, 2013 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-24076472

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: The great potential of phytotherapic drugs for treating and preventing inflammatory diseases mediated by increased neutrophil reactive oxygen species (ROS) generation has guided the search for new natural products with antioxidant and immunomodulatory properties. Baccharis dracunculifolia D.C. (Asteraceae), the main botanical source of Brazilian green propolis, is a native plant from Brazil widely used in folk medicine as anti-inflammatory. This study aims: (a) to determine the influence of seasonality on the chemical profile and biological activity of Baccharis dracunculifolia (Asteraceae) leaf extracts (BdE); (b) to analyze the correlation between the major compounds and the ability of BdE to modulate the superoxide anion and total ROS generation by human neutrophils. MATERIALS AND METHODS: The extracts were obtained from leaf samples collected monthly during one year. The superoxide anion and total ROS generation were assessed by the lucigenin (CL-luc)- and luminol (CL-lum)-enhanced chemiluminescence assays. RESULTS: Seasonality influenced more the quantitative than the qualitative chemical profile of B. dracunculifolia, and affected its biological activity. The major compounds identified were caffeic acid, p-coumaric acid, aromadendrin-4'-methyl ether (AME), isosakuranetin and artepillin C. The IC50 values obtained for CL-lum and CL-luc inhibition by BdE ranged from 8.1-15.8 and 5.8-13.3µgmL(-1), respectively, and correlated positively with caffeic acid concentration. CL-luc inhibition correlated negatively with the concentration of artepillin C, AME, isosakuranetin and total flavonoids. The BdE sample from May/07 inhibited CL-lum and CL-luc the most strongly (IC50=8.1 ± 1.6 and 5.8 ± 1.0 µg mL(-1), respectively), and contained the highest ratio of caffeic acid to the other isolated compounds; so, this ratio could be employed as chemical marker for this biological activity of B. dracunculifolia. CONCLUSION: The ability of B. dracunculifolia to inhibit the neutrophil ROS generation depends more on the type and ratio of phenolic compounds and flavonoids than on their high absolute concentrations. Together, our results help select the most appropriate plant material for the production of phytotherapic drugs to be used in the treatment of inflammatory diseases mediated by increased neutrophil activation.


Assuntos
Baccharis , Neutrófilos/efeitos dos fármacos , Extratos Vegetais/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Adolescente , Adulto , Ácidos Cafeicos/análise , Ácidos Cafeicos/farmacologia , Células Cultivadas , Flavonoides/análise , Flavonoides/farmacologia , Humanos , Neutrófilos/metabolismo , Fenóis/análise , Fenóis/farmacologia , Extratos Vegetais/química , Folhas de Planta , Estações do Ano , Adulto Jovem
12.
Chem Biol Interact ; 206(1): 63-75, 2013 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-23994743

RESUMO

In the present study, we assessed whether 7-hydroxycoumarin (umbelliferone), 7-hydroxy-4-methylcoumarin, and their acetylated analogs modulate some of the effector functions of human neutrophils and display antioxidant activity. These compounds decreased the ability of neutrophils to generate superoxide anion, release primary granule enzymes, and kill Candida albicans. Cytotoxicity did not mediate their inhibitory effect, at least under the assessed conditions. These coumarins scavenged hypochlorous acid and protected ascorbic acid from electrochemical oxidation in cell-free systems. On the other hand, the four coumarins increased the luminol-enhanced chemiluminescence of human neutrophils stimulated with phorbol-12-myristate-13-acetate and serum-opsonized zymosan. Oxidation of the hydroxylated coumarins by the neutrophil myeloperoxidase produced highly reactive coumarin radical intermediates, which mediated the prooxidant effect observed in the luminol-enhanced chemiluminescence assay. These species also oxidized ascorbic acid and the spin traps α-(4-pyridyl-1-oxide)-N-tert-butylnitrone and 5-dimethyl-1-pyrroline-N-oxide. Therefore, 7-hydroxycoumarin and the derivatives investigated here were able to modulate the effector functions of human neutrophils and scavenge reactive oxidizing species; they also generated reactive coumarin derivatives in the presence of myeloperoxidase. Acetylation of the free hydroxyl group, but not addition of the 4-methyl group, suppressed the biological effects of 7-hydroxycoumarin. These findings help clarify how 7-hydroxycoumarin acts on neutrophils to produce relevant anti-inflammatory effects.


Assuntos
Antifúngicos/farmacologia , Antioxidantes/farmacologia , Candida albicans/efeitos dos fármacos , Neutrófilos/efeitos dos fármacos , Umbeliferonas/farmacologia , Ânions/antagonistas & inibidores , Ânions/metabolismo , Antifúngicos/química , Antioxidantes/química , Relação Dose-Resposta a Droga , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Neutrófilos/metabolismo , Espécies Reativas de Oxigênio/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo , Relação Estrutura-Atividade , Umbeliferonas/química
13.
J Med Food ; 16(8): 692-700, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23905650

RESUMO

Increased neutrophil activation significantly contributes to the tissue damage in inflammatory illnesses; this phenomenon has motivated the search for new compounds to modulate their effector functions. Coumarins are natural products that are widely consumed in the human diet. We have evaluated the antioxidant and immunomodulator potential of five 4-methylcoumarin derivatives. We found that the 4-methylcoumarin derivatives inhibited the generation of reactive oxygen species by human neutrophils triggered by serum-opsonized zymosan or phorbol-12-myristate-13-acetate; this inhibition occurred in a concentration-dependent manner, as revealed by lucigenin- and luminol-enhanced chemiluminescence assays. Cytotoxicity did not mediate this inhibitory effect. The 7,8-dihydroxy-4-methylcoumarin suppressed the neutrophil oxidative metabolism more effectively than the 6,7- and 5,7-dihydroxy-4-methylcoumarins, but the 5,7- and 7,8-diacetoxy-4-methylcoumarins were less effective than their hydroxylated counterparts. An analysis of the biochemical pathways suggested that the 6,7- and 7,8-dihydroxy-4-methylcoumarins inhibit the protein kinase C-mediated signaling pathway, but 5,7-dihydroxy-4-methylcoumarin, as well as 5,7- and 7,8-diacetoxy-4-methylcoumarins do not significantly interfere in this pathway of the activation of the human neutrophil oxidative metabolism. The 4-methylcoumarin derivatives bearing the catechol group suppressed the elastase and myeloperoxidase activity and reduced the 1,1-diphenyl-2-picrylhydrazyl free radical the most strongly. Interestingly, the 5,7-dihydroxy-4-methylcoumarin scavenged hypochlorous acid more effectively than the o-dihydroxy-substituted 4-methylcoumarin derivatives, and the diacetoxylated 4-methylcoumarin derivatives scavenged hypochlorous acid as effectively as the 7,8-dihydroxy-4-methylcoumarin. The significant influence of small structural modifications in the inhibitory potential of 4-methylcoumarin derivatives on the effector functions of neutrophil makes them interesting candidates to develop new drugs for the treatment of inflammatory diseases mediated by increased neutrophil activation.


Assuntos
Cumarínicos/farmacologia , Regulação para Baixo/efeitos dos fármacos , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Elastase Pancreática/antagonistas & inibidores , Adulto , Antioxidantes/química , Antioxidantes/farmacologia , Células Cultivadas , Cumarínicos/química , Humanos , Neutrófilos/enzimologia , Elastase Pancreática/metabolismo , Espécies Reativas de Oxigênio/metabolismo
14.
Anal Biochem ; 437(2): 130-2, 2013 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-23499965

RESUMO

This article shows how six vehicles interfere in the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by hypochlorous acid (HOCl) and taurine chloramine in vitro. All the tested vehicles inhibited TMB oxidation by HOCl; dimethyl sulfoxide had a remarkable effect at concentrations as low as 0.00005% (v/v). Cremophor EL and ethanol inhibited TMB oxidation by taurine chloramine at concentrations higher than 0.05 and 25% (v/v), respectively; the other vehicles did not affect this reaction. The results will help to guide the choice of solvent for the TMB oxidation assay performed under viable experimental conditions for evaluation of the HOCl and taurine chloramine scavenging ability of drugs.


Assuntos
Benzidinas/química , Dimetil Sulfóxido/química , Ácido Hipocloroso/química , Taurina/análogos & derivados , Etanol/química , Glicerol/análogos & derivados , Glicerol/química , Oxirredução , Quercetina/química , Taurina/química
15.
Int Immunopharmacol ; 15(2): 387-94, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23333455

RESUMO

Immune complex (IC) deposition in tissues triggers the release of harmful oxidant and lytic compounds by neutrophils. We examined how ten 3-phenylcoumarin derivatives affect the reactive oxygen species (ROS) production by IC-stimulated human neutrophils. Most of the 3-phenylcoumarins inhibited the luminol-enhanced chemiluminescence (CL-lum) more strongly than they inhibited the lucigenin-enhanced chemiluminescence (CL-luc), without clear signs of toxicity. The most effective CL-lum inhibitors, 6,7-dihydroxy-3-[3',4'-methylenedioxyphenyl]-coumarin (5) and 6,7-dihydroxy-3-[3',4'-dihydroxyphenyl]-coumarin (19), also inhibited myeloperoxidase activity more potently and had higher hypochlorous acid scavenging ability, but did not affect the NADPH-oxidase activity. The type, number, and position of the substituent influenced the pharmacological effects of 3-phenylcoumarins; however, the structural requirements for CL-lum and CL-luc inhibition were a little different. Compounds 5 and 19 are promising prototypes of therapeutic molecules to modulate ROS production by neutrophils in IC-mediated inflammatory diseases.


Assuntos
Cumarínicos/farmacologia , Sequestradores de Radicais Livres/farmacologia , Neutrófilos/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Complexo Antígeno-Anticorpo/imunologia , Células Cultivadas , Cumarínicos/química , Descoberta de Drogas , Sequestradores de Radicais Livres/química , Humanos , Doenças do Complexo Imune/imunologia , Imunomodulação , Medições Luminescentes , Terapia de Alvo Molecular , Neutrófilos/imunologia , Oxirredução/efeitos dos fármacos , Peroxidase/metabolismo , Relação Estrutura-Atividade
16.
Immunobiology ; 215(6): 475-85, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19720428

RESUMO

Galectins are beta-galactoside-binding lectins involved in several biological processes and galectin-3 (Gal-3) is related to modulation of immune and inflammatory responses. This study aimed to evaluate the role of Gal-3 in the life span and biological functions of murine neutrophils during in vitro infection by virulent Toxoplasma gondii RH strain. Inflammatory peritoneal neutrophils (Nphi) from C57BL/6 wild-type (WT) and Gal-3 knockout (KO) mice were cultured in the presence or absence of parasites and analyzed for phosphatidylserine (PS) exposure and cell death using Annexin-V and propidium iodide staining, and cell viability by MTT assay. Cell toxicities determined by lactate dehydrogenase (LDH), degranulation by lysozyme release, and cytokine production were measured in Nphi culture supernatants. Phorbol myristate acetate (PMA)- or zymosan-dependent reactive oxygen species (ROS) were measured in Nphi cultures. Our results demonstrated that Gal-3 is involved in the increase of the viable Nphi number and the decrease of PS exposure and cell death following T. gondii infection. We also observed that Gal-3 downmodulates T. gondii-induced Nphi toxicity as well as Nphi degranulation regardless of infection. Furthermore, Gal-3 expression by Nphi was associated with increased levels of IL-10 in the beginning and decreased levels of TNF-alpha later on, regardless of parasite infection, as well as with decreased levels of IL-6 and increased IL-12 levels, following early parasite infection. Our results also showed that Gal-3 suppresses PMA- but not zymosan-induced ROS generation in Nphi following T. gondii infection. In conclusion, Gal-3 plays an important modulatory role by interfering in Nphi life span and activation during early T. gondii infection.


Assuntos
Galectina 3/imunologia , Regulação da Expressão Gênica/imunologia , Ativação de Neutrófilo/imunologia , Neutrófilos/imunologia , Toxoplasma/imunologia , Toxoplasmose/imunologia , Animais , Degranulação Celular/genética , Degranulação Celular/imunologia , Células Cultivadas , Citocinas/biossíntese , Citocinas/imunologia , Galectina 3/genética , Galectina 3/metabolismo , Regulação da Expressão Gênica/genética , Camundongos , Camundongos Knockout , Ativação de Neutrófilo/genética , Neutrófilos/metabolismo , Espécies Reativas de Oxigênio/imunologia , Espécies Reativas de Oxigênio/metabolismo , Toxoplasma/metabolismo , Toxoplasmose/genética , Toxoplasmose/metabolismo
17.
Food Chem Toxicol ; 47(1): 163-70, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19022329

RESUMO

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 [IC50 (in microg/10(6)cells)=115.7+/-9.7 (LumCL) and 174.5+/-25.9 (LucCL)], than the OZ- [IC50=248.5+/-23.1 (LumCL) and 324.1+/-34.6 (LucCL)] or fMLP-stimulated cells [IC50=178.5+/-12.2 (LumCL)]. The ExT also inhibited neutrophil NADPH oxidase activity (evaluated by O2 consumption), degranulation and elastase activity (evaluated by spectrophotometric methods) at concentrations higher than 200 microg/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.


Assuntos
Frutas/química , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Extratos Vegetais/farmacologia , Tamarindus/química , Antioxidantes/química , Antioxidantes/farmacologia , Degranulação Celular/efeitos dos fármacos , Células Cultivadas , Feminino , Humanos , Medições Luminescentes , Masculino , NADPH Oxidases/antagonistas & inibidores , Elastase Pancreática/antagonistas & inibidores , Ésteres de Forbol , Extratos Vegetais/química , Espécies Reativas de Oxigênio/metabolismo
18.
Eur J Med Chem ; 43(5): 996-1007, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-17804122

RESUMO

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.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Complexo Antígeno-Anticorpo/fisiologia , Cumarínicos/farmacologia , Neutrófilos/efeitos dos fármacos , Relação Quantitativa Estrutura-Atividade , Explosão Respiratória , Animais , Anti-Inflamatórios não Esteroides/química , Cumarínicos/química , Feminino , Interações Hidrofóbicas e Hidrofílicas , Técnicas In Vitro , Medições Luminescentes , Modelos Moleculares , Neutrófilos/metabolismo , Coelhos , Espécies Reativas de Oxigênio/metabolismo
19.
Clin Rheumatol ; 27(6): 701-8, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17955277

RESUMO

To determine the relation between neutrophil function and the clinical characteristics of systemic lupus erythematosus (SLE), the superoxide anion (O2-) production by neutrophils, mediated by FcgammaR and FcgammaR/CR cooperation, was studied in 64 SLE patients classified according to their prevalent clinical manifestations. Three clinically distinct patterns were designated: (1) manifestations associated with the occurrence of cytotoxic antibodies (SLE-I group); (2) manifestations associated with circulating immune complexes (IC; SLE-II group), and (3) manifestations associated with IC and cytotoxic antibodies (SLE-III group). O2- production was evaluated by a lucigenin-dependent chemiluminescent assay in neutrophils stimulated with IC-IgG opsonized or not with complement. No difference in O2- production was observed when neutrophil responses from healthy controls were compared to the unclassified patients. However, when the SLE patient groups were considered, the following differences were observed: (1) SLE-I neutrophils showed lower O2- production mediated by the IgG receptor (FcgammaR) with the cooperation of complement receptors (FcgammaR/CR) than observed in the SLE-II, SLE-III, and healthy groups; (2) neutrophils from the SLE-II group showed a decreased [Formula: see text] production mediated by FcgammaR/CR compared to the SLE-III group, (3) SLE-III neutrophils produced more O(2)(-) than neutrophils from the SLE-II and control groups, and (4) CR showed inefficiency in mediating the O2- production by neutrophils from the SLE-I group. Comparative experiments on the kinetics of chemiluminescence (CL; Tmax and CLmax) disclosed differences only for the SLE-I group. Taken together, these results suggest that differences in oxidative metabolism of neutrophils mediated by FcgammaR/CR may reflect an acquired characteristic of disease associated with distinct clinical manifestations.


Assuntos
Lúpus Eritematoso Sistêmico/imunologia , Lúpus Eritematoso Sistêmico/metabolismo , Neutrófilos/metabolismo , Superóxidos/metabolismo , Adulto , Idoso , Autoanticorpos/sangue , Feminino , Humanos , Cinética , Luminescência , Lúpus Eritematoso Sistêmico/epidemiologia , Masculino , Pessoa de Meia-Idade , Receptores de Complemento/metabolismo , Receptores de IgG/metabolismo , Estudos Soroepidemiológicos
20.
Z Naturforsch C J Biosci ; 62(5-6): 339-47, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17708437

RESUMO

Extracts from Alternanthera maritima are used in Brazilian folk medicine for the treatment of infectious and inflammatory diseases. Bioassay-guided fractionation of A. maritima aerial parts yielded an ethanolic crude extract, its butanolic fraction and seven isolated flavonoids (two aglycones, two O-glycosides and three C-glycosides) with antioxidative activity. The ability of these samples to scavenge enzymatically generated free radicals (luminol-horseradish peroxidase-H2O2 reaction) and inhibit reactive oxygen species (ROS) production by opsonized zymosan-stimulated human neutrophils (PMNLs) was evaluated by chemiluminescence methods. In both assays, the butanolic fraction was significantly more active than the ethanolic crude extract, the flavonoid aglycones had high inhibitory activities and the C-glycosylated flavonoids had no significant effect even at the highest concentration tested (50 micromol/L). However, the O-glycosylated flavonoids inhibitory effects on chemiluminescence were strongly dependent on the chemical structure and assay type (cellular or cell-free system). Under the conditions tested, active samples were not toxic to human PMNLs.


Assuntos
Amaranthaceae/química , Sobrevivência Celular/efeitos dos fármacos , Sequestradores de Radicais Livres/isolamento & purificação , Neutrófilos/fisiologia , Componentes Aéreos da Planta/química , Extratos Vegetais/isolamento & purificação , Antioxidantes/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Sistema Livre de Células , Etanol , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/farmacologia , Glicosídeos/isolamento & purificação , Glicosídeos/farmacologia , Humanos , Cinética , Luminescência , Neutrófilos/citologia , Neutrófilos/efeitos dos fármacos , Extratos Vegetais/química , Extratos Vegetais/farmacologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...