RESUMEN
Aedes aegypti is the main urban vector of dengue virus, chikungunya virus and Zika virus due to its great dispersal capacity and virus susceptibility. A. aegypti feed on plant-derived sugars but females need a blood meal for egg maturation. Haematophagous arthropods need to overcome host haemostasis and local immune reactions in order to take a blood meal. In this context, molecules present in the saliva and/or intestinal contents of these arthropods must contain inhibitors of the complement system (CS). CS salivary and/or intestinal inhibitors are crucial to protect gut cells of haematophagous arthropods against complement attack. The present work aimed to investigate the anti-complement activity of A. aegypti intestinal contents on the alternative, classical and lectin pathways of the human complement system. Here we show that A. aegypti gut contents inhibited the human classical and the lectin pathways but not the alternative pathway. The A. aegypti gut content has a serine protease able to specifically cleave and inactivate human C4, which is a novel mechanism for human complement inactivation in haematophagous arthropods. The gut of female A. aegypti was capable of capturing human serum factor H (a negative complement modulator), unlike males. C3 molecules in recently blood-fed female A. aegypti remain in their original state, being inactivated to iC3b soon after a blood feed. A transmission-blocking vaccine using these complement inhibitory proteins as antigens has the potential to interfere with the insect's survival, reproductive fitness and block their infection by the arboviruses they transmit to humans.
Asunto(s)
Aedes/fisiología , Fiebre Chikungunya/prevención & control , Proteínas Inactivadoras de Complemento/metabolismo , Dengue/prevención & control , Microbioma Gastrointestinal/fisiología , Infección por el Virus Zika/prevención & control , Aedes/microbiología , Américas , Animales , Virus Chikungunya/fisiología , Virus del Dengue/fisiología , Femenino , Masculino , Mosquitos Vectores/microbiología , Mosquitos Vectores/fisiología , Virus Zika/fisiologíaRESUMEN
The aim of this study was to chemically characterize an arabinogalactan-protein-rich fraction (FRAGP) obtained from an aqueous extract of avocado leaves and investigate its effects on the classical pathway of the complement system. The FRAGP contained 4.6%⯱â¯1.8%, 22.5%⯱â¯4.9%, and 76.7%⯱â¯8.8% of total protein, arabinogalactan-protein, and carbohydrates, respectively. Arabinose and galactose were the main monosaccharide constituents. FT-IR and NMR data, together with linkage analyses, indicated the presence of a structure that included a (1â¯ââ¯3)-linked ß-D-Galp main chain, mainly substituted at O-6 by Gal and Ara residues, which was characteristic of a type II arabinogalactan. The effect of FRAGP on the classical pathway of complement system was examined by a hemolytic fixation test and comparing with heparin, which was used as a control for inhibition. With pre-incubation, the IC50 of FRAGP was 1.90⯱â¯1.1⯵g/mL, which was similar to that of heparin (IC50â¯=â¯2.90⯱â¯0.3⯵g/mL). Without pre-incubation, the IC50 values were 18.6⯱â¯3.7 and 8.0⯱â¯4.1⯵g/mL for FRAGP and heparin, respectively. Collectively, these results suggested that FRAGP has an inhibitory effect on the classical pathway of the complement system.
Asunto(s)
Proteínas Inactivadoras de Complemento/química , Proteínas del Sistema Complemento/química , Mucoproteínas/química , Persea/química , Arabinosa/química , Proteínas Inactivadoras de Complemento/farmacología , Proteínas del Sistema Complemento/efectos de los fármacos , Galactanos/química , Galactosa/química , Heparina/química , Humanos , Espectroscopía de Resonancia Magnética , Mucoproteínas/aislamiento & purificación , Mucoproteínas/farmacología , Extractos Vegetales/química , Extractos Vegetales/farmacología , Hojas de la Planta/química , Proteínas de Plantas/química , Proteínas de Plantas/aislamiento & purificación , Proteínas de Plantas/farmacología , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
BACKGROUND: Rhipicephalus (Boophilus) microplus is the main ectoparasite affecting livestock worldwide. For a successful parasitism, ticks need to evade several immune responses of their hosts, including the activation of the complement system. In spite of the importance of R. microplus, previous work only identified one salivary molecule that blocks the complement system. The current study describes complement inhibitory activities induced by R. microplus salivary components and mechanisms elicited by putative salivary proteins on both classical and alternative complement pathways. RESULTS: We found that R. microplus saliva from fully- and partially engorged females was able to inhibit both pathways. Saliva acts strongly at the initial steps of both complement activation pathways. In the classical pathway, the saliva blocked C4 cleavage, and hence, deposition of C4b on the activation surface, suggesting that the inhibition occurs at some point between C1q and C4. In the alternative pathway, saliva acts by binding to initial components of the cascade (C3b and properdin) thereby preventing the C3 convertase formation and reducing C3b production and deposition as well as cleavage of factor B. Saliva has no effect on formation or decay of the C6 to C8 components of the membrane attack complex. CONCLUSION: The saliva of R. microplus is able to inhibit the early steps of classical and alternative pathways of the complement system. Saliva acts by blocking C4 cleavage and deposition of C4b on the classical pathway activation surface and, in the alternative pathway, saliva bind to initial components of the cascade (C3b and properdin) thereby preventing the C3 convertase formation and the production and deposition of additional C3b.
Asunto(s)
Proteínas Inactivadoras de Complemento/metabolismo , Vía Alternativa del Complemento/efectos de los fármacos , Vía Clásica del Complemento/efectos de los fármacos , Rhipicephalus/inmunología , Saliva/metabolismo , Animales , Evasión Inmune , Tolerancia InmunológicaRESUMEN
O Angioedema Hereditário (AEH) é uma doença resultante de distúrbios nos sistemas complemento, da coagulação e calicreína-bradicinina. A doença manifesta-se por edema subcutâneo, dor abdominal e edema de laringe com morte por asfixia. Trauma, estresse e ciclo menstrual podem desencadear as crises. O AEH tipo I é descrito em 85% dos casos com níveis antigênicos e funcionais do inibidor da Cl esterase (C1-INH) reduzidos. No tipo II, o defeito é funcional com níveis de C1-INH normais. No tipo III, não existe alteração do C1-INH e associa-se a elevados níveis de estrogênio exógeno e/ou mutações no gene do fator XII da coagulação. Os níveis de C4 encontram-se reduzidos no HAE tipo I e II. A dosagem de C1q é utilizada para diferenciar o AEH dos casos adquiridos. Na profilaxia em longo prazo recomenda-se o uso de antifibrinoliticos ou andrógenos atenuados caso mais de uma crise grave ocorra ao mês e quando o tratamento para os ataques não forem eficazes ou disponíveis. Na profilaxia em curto prazo deve-se usar concentrados do C1-INH, não disponível no Brasil, substituído pelo plasma com eficácia limitada. Nas crises de AEH, o único medicamento disponível em nosso meio é o icatibanto, antagonista do receptor de bradicinina, administrado por via subcutânea. O ecalantide é um inibidor da calicreína usado nas crises também não disponível no Brasil. O AEH é uma doença subdiagnosticada que pode ser controlada evitando-se o óbito por asfixia. Novos tratamentos estão sendo disponibilizados que podem resultar numa melhor qualidade de vida dos pacientes.
Hereditary angioedema (HAE) is a disease caused by disturbs of complement, coagulation and kalikrein-bradikynin systems. The disease presents relapsing subcutaneous swelling, abdominal pain and laryngeal edema causing asphyxia. Trauma, stress and menses can precipitate the attacks. HAE Type I is described in 85% of the cases with reduced antigenic and functional levels of the C-1 esterase inhibitor (C1-INH). In Type II, the defect is functional and C1-INH levels are normal. In type III HAE, there is no impaired C1-INH but high doses of exogenous estrogens and/or mutations in Factor XII gene have been found. C4 levels are reduced in HAE Type I and II. Serum Clq is applied for differential diagnosis of acquired angioedema. Long term prophylaxis is recommended with antifibrinolytic agents or atenuated androgens whether there is more than one severe attack per month and the treatment for the attacks are nor efficacious or available. For short term prophylaxis, C1-INH concentrates should be used, however they are not available in Brazil and it is substituted by plasma with limited efficacy. During HAE attacks, the only drug available in Brasil is icatibant, a bradykinin antagonist receptor. Ecalantide is a kallikrein inhibitor to be used in attacks, not availabie in Brazil yet. Therefore, HAE is a misdiagnosed disease that may be controlled preventing the death due to asphyxia. New treatment options have been available that might result in a better quality of life within the patients.
Asunto(s)
Humanos , Angioedemas Hereditarios , Asfixia , Proteínas Inactivadoras de Complemento , Danazol , Esterasas , Tracto Gastrointestinal , Edema Pulmonar , Tejido Subcutáneo , Sistema Respiratorio/patología , Ácido Tranexámico , Métodos , Pacientes , Métodos , Técnicas y Procedimientos DiagnósticosRESUMEN
Saliva of haematophagous arthropods contain biomolecules involved directly or indirectly with the haematophagy process, and among them are encountered some complement system inhibitors. The most obvious function for these inhibitors would be the protection of the midgut against injury by the complement. To investigate this hypothesis, Triatoma brasiliensis nymphs were forced to ingest human serum in conditions in which the protection of midgut by the inhibitors is bypassed. In these conditions, the anterior midgut epithelium was injured by the complement, causing cell death. Once some insects such as Aedes aegypti have no salivary inhibitors, we hypothesized the existence of intestinal inhibitors. The inhibitory activity was investigated in the intestine of A. aegypti as well as in the saliva and intestine of other three triatomine species (T. brasiliensis, T. infestans and Rhodnius prolixus) using an immunological method able to determine the level of deposition of some complement factors (C1q, C3b, or C4b) on the surface of complement activator molecules linked to microplates. This methodology permitted to identify which points along the activation phase of the complement cascade were inhibited. As expected, soluble contents of A. aegypti's intestine was capable to inhibit C3b deposition by the classical and alternative pathways. Saliva or soluble intestinal contents, obtained from triatomines were unable to inhibit C1q deposition by the classical pathway. C4b deposition by the classical pathway was inhibited by the intestinal contents from the three triatomines. On the other hand, only T. brasiliensis saliva inhibited C4b deposition. Both, saliva and intestinal contents from all triatomines were able to inhibit C3b deposition in the classical and alternative pathways. None of the material extracted from the intestinal cell membranes from the triatomines inhibited C3b deposition in the classical pathway. The existence of complement inhibitors may have important biological consequences which are discussed in detail.
Asunto(s)
Proteínas Inactivadoras de Complemento/metabolismo , Proteínas del Sistema Complemento/metabolismo , Mucosa Intestinal/metabolismo , Glándulas Salivales/metabolismo , Animales , Artrópodos , Culicidae , Colorantes Fluorescentes/farmacología , Hemolinfa/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Microvellosidades/metabolismo , Modelos Biológicos , Modelos EstadísticosRESUMEN
Complement activation is an important step in the acceleration of liposome clearance. The anaphylatoxins released following complement activation may motivate a wide variety of physiologic changes. We performed physicochemical characterization and in vitro studies of the interaction of complement system with both noncirculating and long-circulating pH-sensitive and nonpH-sensitive liposomes. The liposomes were characterized by diameter, zeta potential, and atomic force microscopy (AFM). The study of liposome interactions with complement system was conducted using hemolytic assay in rat serum. All liposomes presented a similar mean diameter (between 99.8 and 124.3 nm). The zeta potential was negative in all liposome preparations, except in liposomes modified with aminopoly (ethyleneglycol) 2000-distearoylphosphatidylethanolamine (aPEG(2000)-DSPE), which presented positive zeta potential. Atomic force microscopy images showed that non-long-circulating pH-sensitive liposomes are prone to vesicles aggregation. Non-pH-sensitive liposomes complement system activates, while pH-sensitive liposomes showed to be poor complement activators in rat serum.
Asunto(s)
Activación de Complemento , Proteínas del Sistema Complemento/química , Liposomas/química , Animales , Colesterol/química , Proteínas Inactivadoras de Complemento/química , Sistemas de Liberación de Medicamentos , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Lípidos/química , Masculino , Membranas/química , Microscopía de Fuerza Atómica , Fosfatidilcolinas/química , Ratas , Ratas WistarRESUMEN
Hyperbilirubinemia and complement-mediated immune attack on hepatocyte membrane are common features of certain hepatic diseases. To assess whether unconjugated bilirubin (UB) counteracts complement-mediated hepatocytolysis, we first generated a rabbit polyclonal antibody (Ab) against rat hepatocyte plasma membrane (RHPM). An assay performed with isolated rat hepatocytes in the presence of the polyclonal Ab and rat serum as complement donor demonstrated that UB inhibits cell lysis, as lactate dehydrogenase release into the medium was inhibited by the pigment in a dose-dependent manner. Immunofluorescence microscopy studies showed that UB significantly attenuates the binding of C3 to the hepatocyte-Ab complex. Further enzyme immunoassay studies showed that UB interferes the binding of C1q to purified anti-RHPM IgG, also in a dose-dependent manner. A dot-blot assay showed that [14C]-UB binds to C1q and human serum albumin (HSA) to a similar extent. A differential spectrum analysis of UB in the presence of C1q further confirmed that the pigment interacts with this protein. In conclusion, we demonstrated an inhibitory action of UB on complement-mediated Ab-induced hepatocytolysis, this action being evidenced at pathophysiological pigment concentrations (171 microM and higher). A direct binding of the pigment to C1q is likely involved.
Asunto(s)
Bilirrubina/farmacología , Membrana Celular/efectos de los fármacos , Complemento C1q/metabolismo , Proteínas Inactivadoras de Complemento/farmacología , Hepatocitos/efectos de los fármacos , Animales , Anticuerpos/inmunología , Bilirrubina/metabolismo , Membrana Celular/inmunología , Células Cultivadas , Complemento C1q/inmunología , Relación Dosis-Respuesta Inmunológica , Técnicas para Inmunoenzimas , L-Lactato Deshidrogenasa/metabolismo , Masculino , Microscopía Fluorescente , Ratas , Ratas WistarRESUMEN
Complement and dendritic cells (DCs) are essential components of innate immunity. Both participate in local inflammation and moreover have roles in the initiation of the acquired immunity response and in the maintenance of tolerance. Recent studies have demonstrated the ability of DCs to synthesize C1q, C3, Factor I, Factor B and complement receptors 3 and 4. In this study, we demonstrate that human DCs are a source of other soluble complement proteins including C1q, C4b binding protein (C4BP), C7 and C8. Complement receptors (CR)1 and the CD18 chain (common for CR3 and CR4) were also present on DCs while CR2 was not detected.
Asunto(s)
Proteínas Inactivadoras de Complemento/biosíntesis , Proteínas del Sistema Complemento/biosíntesis , Células Dendríticas/metabolismo , Monocitos/citología , Receptores de Complemento/biosíntesis , Diferenciación Celular/inmunología , Linaje de la Célula/inmunología , Células Cultivadas , Células Dendríticas/citología , Células Dendríticas/inmunología , Humanos , Inmunidad Innata , Inmunofenotipificación , Macrófagos/inmunología , Macrófagos/metabolismo , Monocitos/inmunología , Monocitos/metabolismoRESUMEN
Activation of the complement system has been shown to play a major role in the mediation of reperfusion injury. Here, we assessed the effects of APT070 (Mirococept), a novel membrane-localised complement inhibitor based on a recombinant fragment of soluble CR1, on the local, remote and systemic injuries following intestinal ischaemia and reperfusion (I/R) in the rat. In a model of mild I/R injury (30 min of ischaemia and 30 min of reperfusion), APT070 dose-dependently (1-10 mg kg(-1)) inhibited the increase in vascular permeability of and neutrophil influx into intestine and lungs. Maximal inhibition occurred at 10 mg kg(-1). Following severe I/R injury (120 min of ischaemia and 120 min of reperfusion), APT070 (10 mg kg(-1)) markedly prevented neutrophil influx and the increase in vascular permeability both in the intestine and the lungs.APT070 also effectively suppressed the increase of tissue (intestine and lungs) and serum concentrations of TNF-alpha and IL-6, but not those of IL-1beta or IL-10. There was no significant reduction of mortality in the APT070 group. In conclusion, treatment with the membrane-targeted complement inhibitor APT070 significantly reduced the hyperinflammatory response after mild and severe ischaemia and reperfusion injury (I/RI) in rats. APT070 may be effective in therapeutic indications involving gut I/RI.
Asunto(s)
Proteínas Inactivadoras de Complemento/uso terapéutico , Proteínas del Sistema Complemento/metabolismo , Gastroenteritis/prevención & control , Intestinos/efectos de los fármacos , Daño por Reperfusión/complicaciones , Animales , Permeabilidad Capilar/efectos de los fármacos , Citocinas/sangre , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Gastroenteritis/sangre , Gastroenteritis/etiología , Gastroenteritis/metabolismo , Hemoglobinas/análisis , Mucosa Intestinal/metabolismo , Intestinos/irrigación sanguínea , Recuento de Leucocitos , Leucocitos/citología , Leucocitos/efectos de los fármacos , Masculino , Neutrófilos/citología , Neutrófilos/efectos de los fármacos , Ratas , Ratas Wistar , Daño por Reperfusión/sangre , Daño por Reperfusión/metabolismoRESUMEN
Calreticulin, a calcium-binding protein that is highly conserved in its multiple functions, is present in a wide spectrum of subcellular compartments in virtually every cell of higher organisms. In this article, we propose a dual role for parasite calreticulin, with emphasis on the Trypanosoma cruzi model. By modulating the vertebrate complement system, calreticulin might provide the parasite with an effective immune-escape mechanism. Alternatively, by inhibiting angiogenesis, the parasite molecule might protect the host from ongoing neoplasic aggressions. Many questions are still unanswered, particularly those regarding the consequences that these interactions could have in vivo for both the parasite and the host.
Asunto(s)
Moduladores de la Angiogénesis/metabolismo , Calreticulina/fisiología , Enfermedad de Chagas/metabolismo , Proteínas Inactivadoras de Complemento/fisiología , Interacciones Huésped-Parásitos/fisiología , Trypanosoma cruzi/metabolismo , Animales , Calreticulina/metabolismo , Proteínas Inactivadoras de Complemento/metabolismo , Proteínas del Sistema Complemento/metabolismo , HumanosRESUMEN
We have examined the role of inflammatory cells, ischemia and serum complement on the development of acute experimental amoebic liver abscess in hamsters (AEALAH). In hamsters made leukopenic by whole body radiation (800 rad) and daily intraperitoneal glycogen injections, the absence of inflammatory cells and liver tissue damage surrounding the parasites resulted in their rapid (24 h) disappearance from the liver, which showed no lesions. Focal liver ischemia, always present in control AEALAH with inflammation and tissue destruction, was reproduced in radiated hamsters by injection of amoebae mixed with Superdex microspheres, but again in the absence of inflammation, amoebae caused no liver damage and disappeared in 24 h. In hamsters made hypocomplementemic by injection of purified cobra venom factor (CVF), amoebae caused AEALA indistinguishable from controls, but in leukopenic + hypocomplementemic hamsters, amoebae were unable to produce lesions and disappeared from the liver in 48 h. We conclude that inflammation and tissue damage are required for the survival of amoebae in AEALAH and for the progression of the experimental disease.
Asunto(s)
Proteínas del Sistema Complemento/inmunología , Entamoeba histolytica/fisiología , Hepatitis/patología , Isquemia/patología , Absceso Hepático Amebiano , Hígado/patología , Enfermedad Aguda , Animales , Proteínas Inactivadoras de Complemento/farmacología , Modelos Animales de Enfermedad , Venenos Elapídicos/farmacología , Entamoeba histolytica/efectos de la radiación , Femenino , Cobayas , Hepatitis/inmunología , Hepatitis/parasitología , Isquemia/inmunología , Isquemia/parasitología , Leucocitos/efectos de la radiación , Leucopenia/etiología , Hígado/inmunología , Hígado/parasitología , Absceso Hepático Amebiano/inmunología , Absceso Hepático Amebiano/parasitología , Absceso Hepático Amebiano/patología , Masculino , Traumatismos Experimentales por RadiaciónRESUMEN
Hereditary (HAE) and acquired (AAE) angioedema are vascular reactions involving the sub mucosal tissues, representing localized edema caused by dilatation and increased permeability of the capillaries. HAE and AAE are clinical disorders characterized by angioedema that require prompt differentiation from other causes of angioedema in order to receive the most pertinent and effective therapeutic interventions. The aim of this report is to describe the clinical characteristics of patients with both HAE and AAE identified and followed at the Immunology Clinic of the University Hospital at the Puerto Rico Medical Center, their response and side effects to danazol therapy and their comparison with other series of similar patients reported in the literature. Overall, the patients in this sample presented a similar clinical profile compared to other reported series in the literature.
Asunto(s)
Angioedema , Adolescente , Adulto , Anciano , Angioedema/diagnóstico , Angioedema/tratamiento farmacológico , Angioedema/genética , Angioedema/inmunología , Niño , Complemento C1/análisis , Complemento C1q/análisis , Complemento C4/análisis , Proteínas Inactivadoras de Complemento/análisis , Danazol/administración & dosificación , Danazol/efectos adversos , Danazol/uso terapéutico , Interpretación Estadística de Datos , Diagnóstico Diferencial , Ensayo de Inmunoadsorción Enzimática , Antagonistas de Estrógenos/administración & dosificación , Antagonistas de Estrógenos/efectos adversos , Antagonistas de Estrógenos/uso terapéutico , Femenino , Humanos , Inmunodifusión , Masculino , Persona de Mediana Edad , Factores de TiempoRESUMEN
The high resistance of Trypanosoma cruzi trypomastigotes, the causal agent of Chagas' disease, to complement involves several parasite strategies. In these in vitro studies, we show that T. cruzi calreticulin (TcCRT) and two subfragments thereof (TcCRT S and TcCRT R domains) bind specifically to recognition subcomponents of the classical and lectin activation pathways (i.e., to collagenous tails of C1q and to mannan-binding lectin) of the human complement system. As a consequence of this binding, specific functional inhibition of the classical pathway and impaired mannan-binding lectin to mannose were observed. By flow cytometry, TcCRT was detected on the surface of viable trypomastigotes and, by confocal microscopy, colocalization of human C1q with surface TcCRT of infective trypomastigotes was visualized. Taken together, these findings imply that TcCRT may be a critical factor contributing to the ability of trypomastigotes to interfere at the earliest stages of complement activation.
Asunto(s)
Calreticulina/fisiología , Proteínas Inactivadoras de Complemento/fisiología , Vía Clásica del Complemento/inmunología , Inmunosupresores , Trypanosoma cruzi/inmunología , Animales , Unión Competitiva/inmunología , Calreticulina/metabolismo , Colágeno/metabolismo , Complemento C1q/antagonistas & inhibidores , Complemento C1q/metabolismo , Proteínas Inactivadoras de Complemento/metabolismo , Humanos , Inmunosupresores/metabolismo , Manosa/metabolismo , Lectina de Unión a Manosa/antagonistas & inhibidores , Lectina de Unión a Manosa/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/fisiología , Microscopía Confocal , Fragmentos de Péptidos/metabolismo , Fragmentos de Péptidos/fisiología , Unión Proteica/inmunología , Estructura Terciaria de Proteína , Trypanosoma cruzi/crecimiento & desarrollo , Trypanosoma cruzi/patogenicidadRESUMEN
Previous studies of human in vivo complement protein levels have only compared data for neonates with that from adult sera. Here, we establish the normal concentration ranges of the following complement regulatory proteins in healthy Brazilian children of different age groups (neonates: 1 month-1 year, 1-6 years and 6-13 years) and in adults: factor H (fH), factor I (fI), C4b-binding protein (C4 BP), properdin and vitronectin. We found that the concentrations of fH, fI, properdin and vitronectin in neonates are significantly lower than in adults. Remarkably, the concentration of C4 BP is below the method resolution (<50 micro g/ml) in 76% of the sera from neonates, while adults presented 199-532 microg/ml of C4 BP in their sera. The concentration of properdin in the sera from neonates and up to 1-year-old children was less than that observed in older children. Adults presented vitronectin levels significantly higher than all the other age groups in the study. No significant sex differences in the concentrations of all the studied regulatory proteins were detected. This study reveals the ontogeny of complement system in greater detail than previously available and may point to the reasons why neonates have higher susceptibility to develop life-threatening pyogenic infections. These reference values will be of use in clinical and laboratory investigations of disorders associated with low levels of these regulatory proteins.
Asunto(s)
Factor H de Complemento/análisis , Proteínas Inactivadoras de Complemento , Fibrinógeno/análisis , Glicoproteínas/análisis , Properdina/análisis , Vitronectina/análisis , Adolescente , Adulto , Factores de Edad , Niño , Preescolar , Humanos , Lactante , Valores de ReferenciaRESUMEN
The effect of the IXalpha isomer of unconjugated bilirubin (UB) on complement-mediated intravascular hemolysis was evaluated in rats carrying naturally occurring heteroantibodies against sheep erythrocytes. Several doses of UB were administered i.v. to these animals in order to induce different levels of hyperbilirubinemia. Intravascular hemolysis was promoted by transfusion with a sheep red cell suspension. Hemoglobin in urine was assessed as a marker of intravascular hemolysis. The urinary excretion of hemoglobin was attenuated by UB in a dose-dependent manner. To establish whether complement was involved in the hemolytic reaction, we evaluated the hemolytic activity of complement in these same animals, before and after sheep erythrocyte transfusion. The significant consumption of complement, which was partially prevented by UB, corroborated its participation in the intravascular hemolytic reaction in the current experimental conditions. The data suggest an inhibitory action of UB on complement-mediated hemolysis in vivo.
Asunto(s)
Bilirrubina/farmacología , Proteínas Inactivadoras de Complemento/farmacología , Eritrocitos/efectos de los fármacos , Hemólisis/efectos de los fármacos , Animales , Proteínas del Sistema Complemento , Relación Dosis-Respuesta a Droga , Eritrocitos/fisiología , Femenino , Técnicas In Vitro , Ratas , Ratas Wistar , OvinosRESUMEN
Trichilia glabra L. aqueous leaf extract exerted a significant antiinflammatory effect 'in vivo' in the zymosan-induced inflammation model. The extract impaired the 'in vitro' activities of polymorphonuclear leukocytes and complement, components of mouse immune system closely related to the inflammatory response induced by zymosan. In particular, a significant reduction in the phagocytic capability and respiratory burst response of mouse polymorphonuclear leukocytes together with an inhibition in the hemolytic activity of mouse complement was observed.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Plantas Medicinales/química , Animales , Proteínas Inactivadoras de Complemento/farmacología , Vía Alternativa del Complemento/efectos de los fármacos , Hemólisis/efectos de los fármacos , Inflamación/inducido químicamente , Inflamación/prevención & control , Ratones , Ratones Endogámicos BALB C , Neutrófilos/efectos de los fármacos , Nitroazul de Tetrazolio , Fagocitosis/efectos de los fármacos , Extractos Vegetales/farmacología , Hojas de la Planta/química , ZimosanRESUMEN
We investigated the in vitro action of the bile pigments, unconjugated bilirubin (UB) and bilirubin monoglucuronide (BMG) on complement (C) cascade reaction. Both UB and BMG inhibited hemolysis in the classical pathway (CP) in a dose-dependent manner at low micromolar concentrations, UB showing a stronger effect than BMG. The analysis of the action of UB on the hemolytic activity of the C1, C4, C2 and C-EDTA components of the C cascade revealed that the C1 step was the most inhibited. An enzyme immunoassay was developed to evaluate the effect of UB on the binding of C1q, one of the subcomponents of C1, to human IgM and IgG. The study demonstrated that the unconjugated pigment interferes both the C1q-IgM and -IgG interactions, thus tentatively explaining the inhibitory action of UB on hemolytic activity of C1. We conclude that the anti-complement effect of UB is mainly exerted on the C1 component, the recognition unit of CP. The potential clinical implication of the reported effects in hyperbilirubinemia is discussed.
Asunto(s)
Bilirrubina/farmacología , Proteínas Inactivadoras de Complemento/farmacología , Proteínas del Sistema Complemento/inmunología , Hemólisis/efectos de los fármacos , Animales , Bilirrubina/análogos & derivados , Células Cultivadas , Complemento C1/inmunología , Complemento C1q/inmunología , Eritrocitos/efectos de los fármacos , Humanos , Técnicas para Inmunoenzimas , Inmunoglobulina G/inmunología , Inmunoglobulina M/inmunología , OvinosRESUMEN
A series of dimeric procyanidins (1-9) and some related polyphenols (10-15) were chosen as model compounds in a comparative investigation for various biological activities in order to obtain structure-activity relationships. Antiviral [herpes simplex virus (HSV) and human immunodeficiency virus (HIV)], antibacterial, superoxide radical-scavenging, and complement-modulating properties were assessed. In general, more pronounced activities were seen with epicatechin-containing dimers for anti-HSV, anti-HIV, and radical-scavenging effects, while the presence of ortho-trihydroxyl groups in the B-ring was important in compounds exhibiting anti-HSV and radical-scavenging effects and complement classical pathway inhibition. Double interflavan linkages gave rise to interesting antiviral effects (HSV and HIV) and complement inhibition. The influence of the degree of polymerization or the type of interflavan linkage (4-->6 or 4-->8) differed in the different biological systems evaluated. Only minor or moderate antibacterial effects were observed for the compounds under investigation.
Asunto(s)
Antocianinas/farmacología , Antiinfecciosos/farmacología , Antivirales/farmacología , Proteínas Inactivadoras de Complemento/farmacología , Flavonoides , Depuradores de Radicales Libres/farmacología , Fenoles/farmacología , Plantas Medicinales/química , Polímeros/farmacología , Antocianinas/química , Antocianinas/aislamiento & purificación , Antibacterianos , Fármacos Anti-VIH/farmacología , Bacterias/efectos de los fármacos , Euphorbiaceae/química , Hemólisis/efectos de los fármacos , Espectroscopía de Resonancia Magnética , Pruebas de Sensibilidad Microbiana , Perú , Simplexvirus/efectos de los fármacosRESUMEN
During their growth in vitro, promastigotes of Leishmania amazonensis undergo differentiation from complement-susceptible to complement-resistant forms. Here, we demonstrate that both forms bind comparable amounts of C3 on their surfaces, with the predominant molecule species being the haemolytically active C3b. Likewise, equivalent amounts of C9 are deposited on both forms of promastigotes. However, while C9-bearing complexes are exposed on the cell surface of resistant promastigotes, they are cryptic in the susceptible stage of the parasites. The membrane fraction of complement-resistant promastigote lysates has the ability to inhibit complement-mediated haemolysis, blocking C9, but not C3 deposition to complement-activating complexes. Moreover, the membrane fraction of complement-resistant promastigote lysates can inhibit the late steps of guinea-pig erythrocyte lysis much more efficiently than complement-susceptible ones. Our results indicate that L. amazonensis promastigotes evade complement killing by inhibiting the cytolytic pathway of the complement cascade.
Asunto(s)
Proteínas del Sistema Complemento/inmunología , Leishmania mexicana/inmunología , Leishmania mexicana/patogenicidad , Animales , Ciclo Celular , Membrana Celular/inmunología , Complemento C3/inmunología , Complemento C3/metabolismo , Complemento C3b/inmunología , Complemento C3b/metabolismo , Complemento C9/inmunología , Complemento C9/metabolismo , Ensayo de Actividad Hemolítica de Complemento , Proteínas Inactivadoras de Complemento , Vía Alternativa del Complemento , Ensayo de Inmunoadsorción Enzimática , Cobayas , Interacciones Huésped-Parásitos , Humanos , Leishmania mexicana/crecimiento & desarrolloRESUMEN
Highly purified Trypanosoma-decay accelerating factor (T-DAF), a 87-93-kD glycoprotein present on the surface of metacyclic and trypomastigote forms of Trypanosoma cruzi, was used as antigen to evaluate the presence of specific serum antibodies in experimentally infected mice and patients with Chagas' disease by enzyme-linked immunosorbent assay (ELISA). Mouse T-DAF antibodies were first recorded on day 7 postinfection, reached maximal concentration on day 30, and maintained at positive titers thereafter. High immunogenicity was clearly demonstrated by the detection of T-DAF antibodies in 96% of the sera collected from chagasic patients in either the acute or the chronic phase of disease. Control sera from normal individuals and from patients with leishmaniasis or other chronic infections did not give positive results. Serologic evaluation using T-DAF as antigen did not discriminate between patients with the cardiac and the digestive forms of the disease. The performance of the T-DAF ELISA was compared with that of conventional screening tests for Chagas' disease (indirect immunofluorescence and hemagglutination). The T-DAF ELISA test showed a sensitivity of 96%, a specificity of 100%, an efficiency of 99%, a positive predicted value of 100%, a negative predicted value of 98%, and a kappa index of 0.96, thus indicating that it can be successfully used for the serodiagnosis of T. cruzi infection in humans.