RESUMO
Mast cells (MCs) are important effectors in allergic reactions since they produce a number of pre-formed and de novo synthesized pro-inflammatory compounds in response to the high affinity IgE receptor (FcεRI) crosslinking. IgE/Antigen-dependent degranulation and cytokine synthesis in MCs have been recognized as relevant pharmacological targets for the control of deleterious inflammatory reactions. Despite the relevance of allergic diseases worldwide, efficient pharmacological control of mast cell degranulation has been elusive. In this work, the xanthone jacareubin was isolated from the heartwood of the tropical tree Callophyllum brasilense, and its tridimensional structure was determined for the first time by X-ray diffraction. Also, its effects on the main activation parameters of bone marrow-derived mast cells (BMMCs) were evaluated. Jacareubin inhibited IgE/Ag-induced degranulation in a dose-response manner with an IC50â¯=â¯46â¯nM. It also blocked extracellular calcium influx triggered by IgE/Ag complexes and by the SERCA ATPase inhibitor thapsigargin (Thap). Inhibition of calcium entry correlated with a blockage on the reactive oxygen species (ROS) accumulation. Antioxidant capacity of jacareubin was higher than the showed by α-tocopherol and caffeic acid, but similar to trolox. Jacareubin shown inhibitory actions on xanthine oxidase, but not on NADPH oxidase (NOX) activities. In vivo, jacareubin inhibited passive anaphylactic reactions and TPA-induced edema in mice. Our data demonstrate that jacareubin is a potent natural compound able to inhibit anaphylactic degranualtion in mast cells by blunting FcεRI-induced calcium flux needed for secretion of granule content, and suggest that xanthones could be efficient anti-oxidant, antiallergic, and antiinflammatory molecules.
Assuntos
Anafilaxia/metabolismo , Cálcio/metabolismo , Mastócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores de IgE/antagonistas & inibidores , Xantonas/farmacologia , Animais , Degranulação Celular/efeitos dos fármacos , Degranulação Celular/fisiologia , Células Cultivadas , Relação Dose-Resposta a Droga , Líquido Extracelular/efeitos dos fármacos , Líquido Extracelular/metabolismo , Masculino , Mastócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Difração de Raios X , Xantonas/isolamento & purificaçãoRESUMO
BACKGROUND: Efficient development of atopic diseases requires interactions between allergen and adjuvant to initiate and amplify the underlying inflammatory responses. Substance P (SP) and hemokinin-1 (HK-1) are neuropeptides that signal through the neurokinin-1 receptor (NK1R) to promote inflammation. Mast cells initiate the symptoms and tissue effects of atopic disorders, secreting TNF and IL-6 after FcεRI cross-linking by antigen-IgE complexes (FcεRI-activated mast cells [FcεRI-MCs]). Additionally, MCs express the NK1R, suggesting an adjuvant role for NK1R agonists in FcεRI-MC-mediated pathologies; however, in-depth research addressing this relevant aspect of MC biology is lacking. OBJECTIVE: We sought to investigate the effect of NK1R signaling and the individual roles of SP and HK-1 as potential adjuvants for FcεRI-MC-mediated allergic disorders. METHODS: Bone marrow-derived mast cells (BMMCs) from C57BL/6 wild-type (WT) or NK1R(-/-) mice were used to investigate the effects of NK1R signaling on FcεRI-MCs. BMMCs generated from Tac1(-/-) mice or after culture with Tac4 small interfering RNA were used to address the adjuvancy of SP and HK-1. WT, NK1R(-/-), and c-Kit(W-sh/W-sh) mice reconstituted with WT or NK1R(-/-) BMMCs were used to evaluate NK1R signaling on FcεRI-MC-mediated passive local and systemic anaphylaxis and on airway inflammation. RESULTS: FcεRI-activated MCs upregulated NK1R and HK-1 transcripts and protein synthesis, without modifying SP expression. In a positive signaling loop HK-1 promoted TNF and IL-6 secretion by MC degranulation and protein synthesis, the latter through the phosphoinositide 3-kinase/Akt/nuclear factor κB pathways. In vivo NK1R signaling was necessary for the development of passive local and systemic anaphylaxis and airway inflammation. CONCLUSIONS: FcεRI stimulation of MCs promotes autocrine secretion of HK-1, which signals through NK1R to provide adjuvancy for efficient development of FcεRI-MC-mediated disorders.
Assuntos
Comunicação Autócrina , Imunoglobulina E/imunologia , Inflamação/imunologia , Inflamação/metabolismo , Mastócitos/imunologia , Mastócitos/metabolismo , Taquicininas/metabolismo , Anafilaxia/imunologia , Anafilaxia/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Interleucina-6/biossíntese , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Camundongos , Camundongos Knockout , Receptores de IgE/metabolismo , Receptores da Neurocinina-1/metabolismo , Transdução de Sinais , Fatores de Necrose Tumoral/biossínteseRESUMO
Stress increases nitric oxide (NO) production in the paraventricular nucleus of the hypothalamus (PVH). Lactation diminishes the response to stress and increases basal NO production markers in the PVH of the dam. This study investigated whether lactation modified the anaphylactic reaction to egg white (EW) injection, and if nitric oxide regulates the neuroendocrine response to this stressor. The activational response of PVH to EW was assessed by c-Fos immunohistochemistry, and NO production was determined by histological staining of NADPH-diaphorase and neuronal nitric oxide synthase (nNOS) and by measuring the concentration of total nitrates and nitrites (NOx) in the hypothalamus of lactating and diestrus rats. EW injection significantly increased the number of Fos-positive neurons in the parvocellular subdivision of the PVH in diestrus, but not in lactating rats. Similarly, EW injection increased the number of NADPH-diaphorase- and nNOS-positive cells in the PVH of diestrus rats, but it did not alter the already increased basal number of NO-positive cells in lactating rats. Furthermore, the total concentration of NOx in the hypothalamus, the circulating level of corticosterone and interleukin-6 increased significantly after EW in diestrus, but not in lactating rats, compared to their corresponding controls. Intracerebral administration of L-NAME, a general NOS inhibitor, reversed the attenuation of the activational response to EW in the PVH of lactating rats. The present results show that lactation diminishes the anaphylactoid reaction to EW compared to that in diestrus rats. This attenuation was absent after L-NAME treatment, suggesting that sustained NO production in the PVH during lactation may limit the neuroendocrine response to stress.
Assuntos
Anafilaxia/fisiopatologia , Lactação/fisiologia , Sistemas Neurossecretores/fisiopatologia , Óxido Nítrico/metabolismo , Núcleo Hipotalâmico Paraventricular/metabolismo , Estresse Fisiológico/fisiologia , Anafilaxia/metabolismo , Animais , Animais Recém-Nascidos , Feminino , Sistemas Neurossecretores/metabolismo , Gravidez , Ratos , Ratos WistarRESUMO
Glycosylation of the Ab molecule is essential for maintaining the functional structure of Fc region and consequently for Ab-mediated effector functions, such as binding to cells or complement system activation. Alterations in the composition of the sugar moiety can dramatically influence Ab activity; however, it is not completely clear how differences in the N-linked oligosaccharide structure impact the biological function of Abs. We have described that murine IgG1 Abs can be separated according to their ability to elicit in vivo anaphylaxis in a fraction of anaphylactic and other of non-anaphylactic molecules. Furthermore, we showed that the N-linked oligosaccharide chain is essential for the structural conformation of the anaphylactic IgG1, the binding to FcgammaRIII on mast cells, and, consequently, for the ability to mediate anaphylactic reactions. In this study, we evaluated the contribution of individual sugar residues to this biological function. Differences in the glycan composition were observed when we analyzed oligosaccharide chains from anaphylactic or non-anaphylactic IgG1, mainly the presence of more sialic acid and fucose residues in anaphylactic molecules. Interestingly, the enzymatic removal of terminal sialic acid residues in anaphylactic IgG1 resulted in loss of the ability to trigger mast cell degranulation and in vivo anaphylactic reaction, similarly to the deglycosylated IgG1 Ab. In contrast, fucose removal did not affect the anaphylactic function. Therefore, we demonstrated that the ability of murine IgG1 Abs to mediate anaphylaxis is directly dependent on the amount of sialic acid residues associated to the oligosaccharide chain attached to the Fc region of these molecules.
Assuntos
Anafilaxia/imunologia , Anafilaxia/metabolismo , Imunoglobulina G/metabolismo , Ácidos Siálicos/metabolismo , Animais , Sítios de Ligação de Anticorpos , Configuração de Carboidratos , Linhagem Celular , Cromatografia de Afinidade , Cromatografia por Troca Iônica , Ensaio de Imunoadsorção Enzimática , Hibridomas , Fragmentos Fc das Imunoglobulinas/química , Fragmentos Fc das Imunoglobulinas/metabolismo , Imunoglobulina G/química , Lectinas/química , Lectinas/imunologia , Lectinas/metabolismo , Mastócitos/química , Mastócitos/imunologia , Mastócitos/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Oligossacarídeos/química , Oligossacarídeos/imunologia , Oligossacarídeos/metabolismo , Ácidos Siálicos/química , Ácidos Siálicos/fisiologia , Relação Estrutura-AtividadeRESUMO
OBJECTIVE: To review the role of nitric oxide production in anaphylaxis. DATA SOURCES: We performed MEDLINE searches of the literature. In addition, some references known to the authors but not listed in MEDLINE, such as abstracts and a CD-ROM, were included. Finally, additional clinical details of the cases were provided by one of the authors. STUDY SELECTION: Primary reports were preferentially selected for inclusion. However, some secondary publications are also cited. RESULTS: Histamine along with other mediators, such as leukotrienes, tumor necrosis factor, and platelet-activating factor, induce the production of nitric oxide. Nitric oxide can inhibit the release and effects of catecholamines. Sympathetic amines may inhibit production of nitric oxide. Studies in animals have demonstrated the generation of nitric oxide during anaphylaxis. Inhibition of nitric oxide synthase improves survival in an animal model of anaphylaxis. Nitric oxide causes vasodilation indirectly by increasing the activation of guanylyl cyclase, which then causes smooth muscle relaxation by increasing the concentration of smooth muscle cyclic guanosine monophosphate. Methylene blue is an inhibitor of guanylyl cyclase, which increases systemic vascular resistance and reverses shock in animal studies. The previously reported successful treatment with methylene blue of 11 patients with anaphylactic hypotension is reviewed. CONCLUSION: Nitric oxide plays a significant role in the pathophysiology of anaphylaxis. Treatment with methylene blue should be considered in patients with anaphylactic hypotension that has not responded to other interventions.
Assuntos
Anafilaxia/metabolismo , Hipotensão/tratamento farmacológico , Azul de Metileno/uso terapêutico , Óxido Nítrico/metabolismo , Anafilaxia/complicações , Anafilaxia/tratamento farmacológico , Animais , Endotélio Vascular/metabolismo , Guanilato Ciclase/antagonistas & inibidores , Guanilato Ciclase/metabolismo , Humanos , Hipotensão/etiologia , Hipotensão/metabolismo , Azul de Metileno/farmacocinética , Modelos Biológicos , Músculo Liso/metabolismoRESUMO
UNLABELLED: The present study investigated the acute inflammatory response (increase in vascular permeability and leukocytes migration) in the pleura of spontaneously hypertensive rats (SHR) and normotensive rats (NTR), using two different stimulus: carrageenan and active anaphylaxis. In addition, the role of endogenous nitric oxide in these responses was investigated. RESULTS: The inflammatory response induced by intrapleural carrageenan injection in SHR developed similarly to that in NTR. Treatment with L-NAME, reduced the intensity of this response in both groups of rats. The inflammatory response induced by active anaphylaxis in SHR and NTR was different. The increase in vascular permeability occurred later in the SHR compared to NTR. The number of leukocyte present in inflammatory exudates was increased at 4 h in both groups of rats. L-NAME treatment did not inhibit exudation at the intervals under analysis, however, reduced the number of mononuclear cells in the inflammatory exudate of SHR. CONCLUSION: The development of the inflammatory response in SHR differs from that in NTR, depending on the nature of the inflammatory stimulus. Endogenous NO plays a clear role in carrageenan-induced inflamma-tion, but not in immunologically mediated inflammation in the analyzed period.
Assuntos
Anafilaxia/complicações , Quimiotaxia de Leucócito , Hipertensão/metabolismo , Leucócitos/imunologia , Óxido Nítrico/metabolismo , Pleurisia/metabolismo , Anafilaxia/induzido quimicamente , Anafilaxia/imunologia , Anafilaxia/metabolismo , Animais , Permeabilidade Capilar , Carragenina , Ensaios de Migração de Leucócitos , Quimiotaxia de Leucócito/efeitos dos fármacos , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Exsudatos e Transudatos/citologia , Exsudatos e Transudatos/metabolismo , Hipertensão/imunologia , Leucócitos/efeitos dos fármacos , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Ovalbumina , Pleurisia/induzido quimicamente , Pleurisia/etiologia , Pleurisia/imunologia , Ratos , Ratos Endogâmicos SHR , Ratos WistarRESUMO
Yangambin was initially selected from a number of lignans isolated from Brazilian plants for its ability to antagonize Platelet-Activating Factor (PAF, 1-O-hexadecyl-2-acetyl- sn-glyceryl-3-phosphorylcholine)-induced biological effects. Subsequently it was shown that, besides its antagonistic properties at PAF receptors, yangambin also prevents the cardiovascular collapse observed during anaphylactic and endotoxic/septic shocks, as well as the vascular and cardiac hyporesponsiveness to catecholamines in endotoxic shock. It is suggested that this naturally occurring compound could be of potential interest in the adjunctive management of the above mentioned pathologies. In the present article, we review the main studies investigating the pharmacological properties of yangambin related to the cardiovascular function.
Assuntos
Fármacos Cardiovasculares/farmacologia , Furanos/farmacologia , Lignanas/farmacologia , Inibidores da Agregação Plaquetária/farmacologia , Glicoproteínas da Membrana de Plaquetas/antagonistas & inibidores , Receptores de Superfície Celular , Receptores Acoplados a Proteínas G , Anafilaxia/tratamento farmacológico , Anafilaxia/metabolismo , Anafilaxia/fisiopatologia , Animais , Plaquetas/metabolismo , Fármacos Cardiovasculares/química , Fármacos Cardiovasculares/uso terapêutico , Furanos/química , Furanos/uso terapêutico , Hemodinâmica/efeitos dos fármacos , Técnicas In Vitro , Lignanas/química , Lignanas/uso terapêutico , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Fator de Ativação de Plaquetas/fisiologia , Inibidores da Agregação Plaquetária/química , Inibidores da Agregação Plaquetária/uso terapêutico , Glicoproteínas da Membrana de Plaquetas/metabolismo , Choque Séptico/tratamento farmacológico , Choque Séptico/metabolismo , Choque Séptico/fisiopatologia , EstereoisomerismoRESUMO
The effects of anaphylaxis on vascular protein extravasation in selected tissues and on the release of prostaglandins in the peritoneal cavity were studied in sensitized rats. Extravasation of Evans blue dye was used as a measure of vascular permeability. Specific antigen challenge increased by 279, 297, 328, 250, and 192% the protein extravasation in the trachea, upper and lower bronchi, pancreas, and duodenum, respectively, but did not modify significantly the vascular permeability of the lung parenchyma, heart, liver, and kidney. Extravasation of Evans blue dye also was increased by 43-fold in the peritoneal cavity. Pretreatment of the animals with indomethacin (10 mg/kg) did not modify significantly the protein extravasation of the trachea, upper and lower bronchi, pancreas, and duodenum induced by anaphylaxis. Pretreatment with a mixture of mepyramine (3 mg/kg) and methysergide (2.5 mg/kg) reduced by 62, 66, and 40% the protein extravasation in the trachea, upper bronchi, and peritoneal cavity, respectively, in similar conditions. The PAF antagonist BN-52021 (5 mg/kg) very strongly reduced the protein extravasation elicited by anaphylaxis in the trachea, upper and lower bronchi, pancreas, and duodenum by 72, 87, 82, 67, and 85%, respectively, and by 53% in the peritoneal cavity. Anaphylaxis also increased the concentrations of thromboxane B2 and leukotriene B4 in the peritoneal exudates, but prostaglandin E2 levels were not affected. Pretreatment with BN-52021 reduced by 29 and 75% the level of thromboxane B2 and leukotriene B4 in the exudates. These results suggest that PAF, histamine, and serotonin mediate the protein extravasation associated with anaphylaxis, whereas prostaglandins are likely to play a minor role in this reaction.
Assuntos
Anafilaxia/metabolismo , Proteínas Sanguíneas/metabolismo , Diterpenos , Eicosanoides/metabolismo , Fator de Ativação de Plaquetas/fisiologia , Animais , Permeabilidade Capilar/fisiologia , Ginkgolídeos , Indometacina/farmacologia , Lactonas/farmacologia , Masculino , Metisergida/farmacologia , Cavidade Peritoneal , Fator de Ativação de Plaquetas/antagonistas & inibidores , Pirilamina/farmacologia , Ratos , Ratos EndogâmicosRESUMO
Serum rat mucosal mast cell protease II (RMCPII) was measured in protein-deficient rats to assess mucosal mast cell (MMC) activation during primary infection with the nematode, Nippostrongylus brasiliensis, and during systemic anaphylaxis produced by Nippostrongylus antigen in immune animals. In the first study, serum RMCPII increased 4-fold by day 15 after infection. By day 20, serum RMCPII continued to rise in protein-deficient animals, but decreased in nutritionally normal animals. This was associated with impaired worm rejection in protein-deficient rats. During systemic anaphylaxis, serum RMCPII was elevated in three groups of protein-deficient rats on 6%, 8% and 10% low protein diets and in nutritionally normal rats. All protein-deficient rats exhibited 3 to 7-fold less mucosal permeability of the small intestine to Evan's blue dye injected intravenously compared to nutritionally normal animals following anaphylactic stimulation. These results demonstrated that MMC are activated during infection in protein deficiency, and suggest that reduced MMC function does not explain delay in worm expulsion. Impaired mucosal anaphylaxis in protein deficiency could not be attributed to a failure of MMC response.
Assuntos
Anafilaxia/metabolismo , Infecções por Nematoides/metabolismo , Deficiência de Proteína/metabolismo , Serina Endopeptidases/sangue , Animais , Antígenos de Helmintos/imunologia , Quimases , Nippostrongylus/imunologia , Nippostrongylus/microbiologia , Ratos , Ratos EndogâmicosRESUMO
Rats with acquired immunity to the intestinal nematode Nippostrongylus brasiliensis develop anaphylaxis after i.v. challenge with an extract of worm antigen, with the small intestine being the primary shock organ. In the present study we have shown that these events were associated with significant elevations in intestinal and plasma concentrations of leukotrienes LTB4 and LTC4. The changes were observed in immune rats over 10-, 30-, and 60-min intervals after antigen challenge but were absent in control animals. These lipid mediators were identified both in the perfusate of the gut lumen, which contained large quantities of mucus, and in homogenates of intestinal tissue. In addition, significant elevations in the concentrations of plasma LTB4 and LTC4 were detected in immune challenged rats but not in controls. Leukotrienes were identified by radioimmunoassay and validated by reverse-phase high-performance liquid chromatography (RP-HPLC). RP-HPLC analysis of SRS-A leukotrienes in immune challenged rats indicated that LTC4 was the predominant sulfidopeptide leukotriene at 10 min, with almost complete biodegradation to LTD4 and LTE4 within 30 min. Infected rats also had significant increases in the numbers of intestinal mucosal mast cells (MMC) and eosinophils. Evidence of MMC activation during anaphylaxis was obtained by showing significant elevations of intestinal and systemic concentrations of their exclusive serine enzyme, rat mast cell proteinase II (RMCPII). Thus, the release of substantial amounts of leukotrienes in the gut and plasma of N. brasiliensis-primed rats after interaction with worm antigens suggests that these potent mediators may play an important role in allergic-type hypersensitivity known to occur during immune reactions against parasitic helminths.