RESUMO
The complement system is essential for host defense, but uncontrolled complement system activation leads to severe, mostly renal pathologies, such as atypical hemolytic uremic syndrome or C3 glomerulopathy. Here, we investigated a novel combinational approach to modulate complement activation by targeting C3 and the terminal pathway simultaneously. The synthetic fusion protein MFHR1 links the regulatory domains of complement factor H (FH) with the C5 convertase/C5b-9 inhibitory fragment of the FH-related protein 1. In vitro, MFHR1 showed cofactor and decay acceleration activity and inhibited C5 convertase activation and C5b-9 assembly, which prevented C3b deposition and reduced C3a/C5a and C5b-9 generation. Furthermore, this fusion protein showed the ability to escape deregulation by FH-related proteins and form multimeric complexes with increased inhibitory activity. In addition to substantially inhibiting alternative and classic pathway activation, MFHR1 blocked hemolysis mediated by serum from a patient with aHUS expressing truncated FH. In FH-/- mice, MFHR1 administration augmented serum C3 levels, reduced abnormal glomerular C3 deposition, and ameliorated C3 glomerulopathy. Taking the unique design of MFHR1 into account, we suggest that the combination of proximal and terminal cascade inhibition together with the ability to form multimeric complexes explain the strong inhibitory capacity of MFHR1, which offers a novel basis for complement therapeutics.
Assuntos
Síndrome Hemolítico-Urêmica Atípica/sangue , Proteínas Sanguíneas/deficiência , Proteínas Inativadoras do Complemento C3b/genética , Inativadores do Complemento/farmacologia , Terapia de Alvo Molecular , Proteínas Recombinantes de Fusão/farmacologia , Animais , Síndrome Hemolítico-Urêmica Atípica/genética , Síndrome Hemolítico-Urêmica Atípica/imunologia , Complemento C3/metabolismo , Convertases de Complemento C3-C5/antagonistas & inibidores , Convertases de Complemento C3-C5/metabolismo , Complemento C3b/antagonistas & inibidores , Proteínas Inativadoras do Complemento C3b/deficiência , Complemento C5/metabolismo , Fator H do Complemento/genética , Inativadores do Complemento/isolamento & purificação , Inativadores do Complemento/uso terapêutico , Complexo de Ataque à Membrana do Sistema Complemento/biossíntese , Via Alternativa do Complemento , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Glomérulos Renais/química , Glomérulos Renais/patologia , Camundongos , Camundongos Knockout , Domínios Proteicos , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/uso terapêuticoRESUMO
To selectively modulate human complement alternative pathway (CAP) activity implicated in a wide range of acute and chronic inflammatory conditions and to provide local cell surface and tissue-based inhibition of complement-induced damage, we developed TT30, a novel therapeutic fusion protein linking the human complement receptor type 2 (CR2/CD21) C3 fragment (C3frag = iC3b, C3dg, C3d)-binding domain with the CAP inhibitory domain of human factor H (fH). TT30 efficiently blocks ex vivo CAP-dependent C3frag accumulation on activated surfaces, membrane attack complex (MAC) formation and hemolysis of RBCs in a CR2-dependent manner, and with a â¼ 150-fold potency gain over fH, without interference of C3 activation or MAC formation through the classic and lectin pathways. TT30 protects RBCs from hemolysis and remains bound and detectable for at least 24 hours. TT30 selectively inhibits CAP in cynomolgus monkeys and is bioavailable after subcutaneous injection. Using a unique combination of targeting and effector domains, TT30 controls cell surface CAP activation and has substantial potential utility for the treatment of human CAP-mediated diseases.
Assuntos
Convertases de Complemento C3-C5/antagonistas & inibidores , Complemento C3d/metabolismo , Fator H do Complemento/uso terapêutico , Via Alternativa do Complemento/imunologia , Descoberta de Drogas , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/uso terapêutico , Doenças do Sistema Imunitário/tratamento farmacológico , Doenças do Sistema Imunitário/imunologia , Receptores de Complemento 3d/uso terapêutico , Proteínas Recombinantes de Fusão/uso terapêutico , Animais , Convertases de Complemento C3-C5/metabolismo , Fator H do Complemento/administração & dosagem , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Feminino , Humanos , Doenças do Sistema Imunitário/metabolismo , Macaca fascicularis , Masculino , Modelos Imunológicos , Terapia de Alvo Molecular/métodos , Coelhos , Receptores de Complemento 3d/administração & dosagem , Proteínas Recombinantes de Fusão/administração & dosagemAssuntos
Anticorpos Monoclonais/farmacologia , Inflamação/terapia , Proteínas de Membrana/imunologia , Receptores de Complemento/imunologia , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais Humanizados , Convertases de Complemento C3-C5/antagonistas & inibidores , Convertases de Complemento C3-C5/metabolismo , Complexo de Ataque à Membrana do Sistema Complemento/efeitos dos fármacos , Complexo de Ataque à Membrana do Sistema Complemento/metabolismo , Proteínas do Sistema Complemento/imunologia , Terapias Complementares , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Receptor da Anafilatoxina C5a , Receptores de Complemento/genética , Receptores de Complemento/metabolismoRESUMO
Boswellic acids (BA), an anti-inflammatory and anti-arthritic principle/s of Boswellia serrata, were found to possess anticomplementary activity. It inhibits the in vitro immunohaemolysis of antibody-coated sheep erythrocytes by pooled guinea-pig serum. The reduced immunohaemolysis was found to be due to inhibition of C3-convertase of the classical complement pathway. The threshold concentration for inhibiting C3-convertase was found to be 100 micrograms. However, higher concentrations of BA showed constant inhibitory effects on immunohaemolysis. BA also exhibited weak inhibitory effects on individual components of the complement system. In vivo administration of BA also showed the inhibitory effect on guinea-pig serum.