RESUMO
To investigate the in vivo role of complement component C5 it is common to compare the inflammatory response between C5-normal and C5-deficient inbred mice strains. Nevertheless, it should be expected that differences in the genetic backgrounds between those strains may affect several physiological parameters, complicating the correct interpretation of results. The use of congenic mice, developed by backcrossing, is therefore preferred. Still, several physiological parameters may be distinctive in the normal and deficient strains and therefore require careful analysis before animals are selected for investigation. We generated two congenic mouse strains: C57BL/6 (B6) C5(-), derived from the parental B6 C5(+) strain and A/J C5(+) mice derived from the parental A/J C5(-) strain. After confirmation by nucleotide sequencing, immunodiffusion and hemolytic activity analysis, several basal physiological parameters were analyzed in the congenic and parental strains before antigen exposition. Serum levels of liver alanine aminotransferase, alkaline phosphatase, albumin, triglycerides, cholesterol and uric acid were found to be different in C5-sufficient and C5-deficient mice from one or both genetic backgrounds (B6 and/or A/J). On the other hand, serum levels of liver aspartate aminotransferase, glucose and urea were not affected by the presence of C5 in either strain. Furthermore, in some cases, C5-dependent variations in these parameters were more evident in mice of the same gender. We conclude here that C5-deficient mice strains may present distinct systemic behaviors which should be taken in consideration before differences in the immune responses are attributed solely to the lack of circulating C5.
Assuntos
Complemento C5/genética , Camundongos Congênicos/fisiologia , Camundongos Endogâmicos C57BL/fisiologia , Alanina Transaminase/metabolismo , Albuminas/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Sequência de Bases , Colesterol/metabolismo , Complemento C5/deficiência , Complemento C5/imunologia , Cruzamentos Genéticos , Feminino , Expressão Gênica , Heterogeneidade Genética , Loci Gênicos , Fígado/enzimologia , Masculino , Camundongos , Especificidade da Espécie , Triglicerídeos/metabolismo , Ácido Úrico/metabolismoRESUMO
Enhanced respiratory syncytial virus disease, a serious pulmonary disorder that affected recipients of an inactivated vaccine against respiratory syncytial virus in the 1960s, has delayed the development of vaccines against the virus. The enhanced disease was characterized by immune complex-mediated airway hyperreactivity and a severe pneumonia associated with pulmonary eosinophilia. In this paper, we show that complement factors contribute to enhanced-disease phenotypes. Mice with a targeted disruption of complement component C5 affected by the enhanced disease displayed enhanced airway reactivity, lung eosinophilia, and mucus production compared to wild-type mice and C5-deficient mice reconstituted with C5. C3aR expression in bronchial epithelial and smooth muscle cells in the lungs of C5-deficient mice was enhanced compared to that in wild-type and reconstituted rodents. Treatment of C5-deficient mice with a C3aR antagonist significantly attenuated airway reactivity, eosinophilia, and mucus production. These results indicate that C5 plays a crucial role in modulating the enhanced-disease phenotype, by affecting expression of C3aR in the lungs. These findings reveal a novel autoregulatory mechanism for the complement cascade that affects the innate and adaptive immune responses.
Assuntos
Hiper-Reatividade Brônquica/imunologia , Complemento C5/metabolismo , Proteínas de Membrana/metabolismo , Eosinofilia Pulmonar/imunologia , Receptores de Complemento/metabolismo , Infecções por Vírus Respiratório Sincicial/fisiopatologia , Vírus Sincicial Respiratório Humano/patogenicidade , Animais , Hiper-Reatividade Brônquica/fisiopatologia , Hiper-Reatividade Brônquica/virologia , Complemento C3a/metabolismo , Complemento C5/deficiência , Regulação para Baixo , Proteínas de Membrana/deficiência , Camundongos , Pneumonia Viral/imunologia , Pneumonia Viral/fisiopatologia , Pneumonia Viral/virologia , Eosinofilia Pulmonar/fisiopatologia , Eosinofilia Pulmonar/virologia , Receptores de Complemento/deficiência , Infecções por Vírus Respiratório Sincicial/imunologia , Infecções por Vírus Respiratório Sincicial/virologia , Índice de Gravidade de DoençaRESUMO
The aim of this work was to investigate the contribution of complement C5-mediated mechanisms, with an emphasis on inflammation, to host defences against Echinococcus granulosus hydatid disease. Thus, we compared the systemic and local inflammatory responses induced by the parasite, and the outcome of infection, between congenic C5-sufficient (B10.D2 n/SnJ) and C5-deficient (B10.D2 o/SnJ) mice challenged with protoscoleces. Indirect evidence of in-vivo complement activation during the establishment phase was obtained; infection induced serum amyloid P and eosinophil responses which were dependent on C5. Early recruitment of polymorphonuclear cells was not dependent on the presence of C5. The higher capacity of C5-sufficient mice to recruit eosinophils was also observed during the cystic phase of infection, and mice recruiting more eosinophils developed lower parasite masses. Analysis of the outcome of infection after 8 months showed that C5-sufficient mice were more resistant to infection than C5-deficient mice in terms of individuals with no cysts; this trend was not statistically significant. In addition, C5-deficient mice developed higher numbers of large (> 5 mm in diameter) cysts and higher cyst weights than C5-sufficient mice indicating that C5-mediated mechanisms are detrimental for parasite growth. Taken together, our results suggest that complement, through C5-mediated effectors, contributes to host defences by both restricting the establishment of infection and controlling the growth of established cysts. This contribution may, at least partially, be associated with the ability of C5a to promote eosinophil infiltration.
Assuntos
Complemento C5/imunologia , Equinococose/imunologia , Echinococcus/imunologia , Animais , Ativação do Complemento , Complemento C3/metabolismo , Complemento C5/deficiência , Complemento C5/metabolismo , Equinococose/parasitologia , Eosinófilos/imunologia , Feminino , Inflamação/imunologia , Macrófagos Peritoneais/imunologia , Camundongos , Neutrófilos/imunologia , Componente Amiloide P Sérico/análiseRESUMO
1. Trypanosoma cruzi epimastigote forms are very rapidly removed from the circulation of normal and C5-deficient mice. Depletion of C3 by cobra venom factor results in a significant delay in parasite clearance. 2. During parasite clearance there is a significant decrease in the number of circulating platelets and parasite clearance is considerably delayed in thrombocytopenic animals. 3. In vitro incubation of epimastigote forms with normal mouse serum leads to the formation of parasite clumps provided that platelets are present. Innactivation of factor B or depletion of C3 prevents this phenomenon. 4. When epimastigotes are incubated with normal mouse serum they absorb one or more factors required for their aggregation with platelets. 5. It is suggested that in mice T. cruzi epimastigote forms are removed from circulation by the alternative pathway of complement activation and that both C3 and platelets are required for parasite clearance
Assuntos
Animais , Camundongos , Plaquetas/parasitologia , Complemento C3/metabolismo , Complemento C5/deficiência , Trypanosoma cruzi/fisiologia , Ativação do Complemento , Camundongos Endogâmicos A , Camundongos Endogâmicos BALB C , Agregação PlaquetáriaRESUMO
The data that are being accumulated on the mechanisms by which pemphigus autoantibodies induce acantholysis in vivo conform that tissue injury in pemphigus is a complex phenomenon where several effector mechanisms may interact. Active research is being performed in many laboratories around the world, employing both in vitro and now in vivo models to further define this unique autoimmune disease.
Assuntos
Acantólise/imunologia , Doenças Autoimunes/imunologia , Modelos Animais de Doenças , Pênfigo/patologia , Acantólise/tratamento farmacológico , Acantólise/patologia , Corticosteroides/farmacologia , Corticosteroides/uso terapêutico , Animais , Animais Recém-Nascidos , Antígenos de Superfície/imunologia , Autoanticorpos/imunologia , Autoanticorpos/toxicidade , Doenças Autoimunes/patologia , Brasil , Ativação do Complemento , Complemento C5/deficiência , Epiderme/imunologia , Haplorrinos , Imunoglobulina G/toxicidade , Camundongos , Camundongos Endogâmicos BALB C , Pênfigo/classificação , Pênfigo/imunologia , Ativadores de Plasminogênio/fisiologia , CoelhosRESUMO
Passive transfer of immune serum obtained from mice chronically infected with Trypanosoma cruzi to mice containing circulating bloodstream trypomastigotes induces a very fast clearance of the parasites. Comparison of trypomastigotes clearance in normocomplementemic and C5-deficient mice showed no difference. IgG fraction obtained from immune serum was very efficient at inducing complement-mediated lysis and immune clearance of bloodstream trypomastigotes, whereas its Fc-missing F (ab') 2 fragments, although able to induce lysis, were unable to induce clearance. It is suggested that the immune clearance of bloodstream trypomastigotes is dependent on the antibody Fc region and that complement-mediated lysis is not a prerequisite for elimination of the parasites from circulation.
Assuntos
Doença de Chagas/imunologia , Imunização Secundária , Fragmentos Fc das Imunoglobulinas/imunologia , Animais , Anticorpos Antiprotozoários/imunologia , Doença de Chagas/terapia , Complemento C5/deficiência , Feminino , Fragmentos Fab das Imunoglobulinas/imunologia , Masculino , Camundongos , Camundongos EndogâmicosRESUMO
We report a patient who developed recurrent urticaria and angioedema at age 2 years, severe hypocomplementemic glomerulonephritis at 11 years, and end-stage renal disease at 14 years. His disease resembled the hypocomplementemic vasculitis syndrome but was atypical in its early age of presentation, severe hypocomplementemia, and progression to end-stage renal disease. Serum C1q levels were extremely low, and C4, C2, C3, and C5 levels were significantly reduced. Serum C1 inhibitor (C1INH) levels were slightly low, presumably from consumption. Circulating C1INH-C1r-C1s complexes were evidenced by reduced ratios of functional to antigenic C1INH and antigenic C1r to C1s. Family members had normal functional and antigenic levels of all complement components studied. The patient's serum, erythrocytes, platelets, and mononuclear cells did not activate complement when mixed with normal target serum. Absence of a circulating complement activator and the low serum C3 and C5 levels suggested the presence of a solid-phase complement activator, possibly related to renal or systemic vascular endothelium. As in patients with homozygous deficiencies of classical pathway components, a severe, prolonged, acquired C1q deficiency may have predisposed this patient to the development of glomerulonephritis.
Assuntos
Proteínas do Sistema Complemento/deficiência , Angioedema/etiologia , Angioedema/imunologia , Criança , Enzimas Ativadoras do Complemento/sangue , Enzimas Ativadoras do Complemento/deficiência , Enzimas Ativadoras do Complemento/metabolismo , Ativação do Complemento , Complemento C1/metabolismo , Proteínas Inativadoras do Complemento 1/deficiência , Proteínas Inativadoras do Complemento 1/metabolismo , Complemento C1q , Complemento C1r , Complemento C1s , Complemento C2/deficiência , Complemento C3/deficiência , Complemento C4/deficiência , Complemento C5/deficiência , Proteínas do Sistema Complemento/metabolismo , Glomerulonefrite/etiologia , Glomerulonefrite/imunologia , Humanos , Masculino , SíndromeRESUMO
Intraperitoneal inoculation of BIO.A mice with P. brasiliensis induces an acute inflammatory infiltrate in which 40-50% of the cells are PMN leucocytes. Previous depletion of serotonin, prostaglandin, histamine and complement does not alter the course of inflammation. Complement-derived factors appear to have no active participation in the process since C5-deficient mice depleted or not by Cobra venom factor (CoF) show the same kind of cellular influx. On the other hand, peritoneal cells incubated (6 h) with the fungus release a soluble factor that induces in vivo an active chemotaxis of PMN cells when inoculated i.p. The factor has the following characteristics: a) it is produced by adherent cells; b) it is protein in nature; c) its production is inhibited by incubation of peritoneal cells with 10 micrograms/ml puromycin and d) it has a molecular weight less than 15 000 daltons, as determined by gel filtration through a Sephadex G-75 column.