RESUMO
OBJECTIVES: To characterize the in vitro binding and effector function properties of CD20-directed small modular immunopharmaceutical (SMIP) 2LM20-4, and to compare its in vivo B-cell depletion activity with the mutated 2LM20-4 P331S [no in vitro complement-dependent cytotoxicity (CDC)] and rituximab in cynomolgus monkeys. METHODS: Direct binding is examined in flow cytometry, confocal microscopy, scatchard and lipid raft assays. Effector function assays include CDC and Fc-mediated cellular toxicity. In the 6-month-long in vivo B-cell depletion study, single i.v. dosages of 1 or 10 mg/kg of anti-CD20 proteins were administered to monkeys and B-cell counts were monitored in peripheral blood, bone marrow and lymph nodes. RESULTS: 2LM20-4 has lower saturation binding to human primary B cells and recruits fewer CD20 molecules into lipid rafts compared with rituximab; however, it induces higher in vitro CDC. In competitive binding, 2LM20-4 only partially displaces rituximab, suggesting that it binds to a fraction of CD20 molecules within certain locations of the plasma membrane as compared with rituximab. In monkeys, 2LM20-4 had more sustained B-cell depletion activity than rituximab in peripheral blood and had significantly more profound and sustained activity than 2LM20-4 P331S and rituximab in the lymph nodes. CONCLUSIONS: SMIP 2LM20-4, which binds to a fraction of CD20 molecules as compared with rituximab, has more potent in vitro CDC, and more potent and sustained B-cell depletion activity in cynomolgus monkeys. Our work has considerable clinical relevance since it provides novel insights related to the emerging B-cell depletion therapies in autoimmune diseases.
Assuntos
Citotoxicidade Celular Dependente de Anticorpos/efeitos dos fármacos , Antígenos CD20/efeitos dos fármacos , Antígenos CD20/imunologia , Anticorpos de Cadeia Única/farmacologia , Animais , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais Murinos/farmacologia , Citotoxicidade Celular Dependente de Anticorpos/imunologia , Linfócitos B/imunologia , Linfócitos B/metabolismo , Sítios de Ligação , Células Cultivadas , Modelos Animais de Doenças , Humanos , Fatores Imunológicos/farmacologia , Técnicas In Vitro , Modelos Lineares , Macaca fascicularis , Distribuição Aleatória , Rituximab , Sensibilidade e EspecificidadeRESUMO
OBJECTIVE: Interleukin-21 (IL-21) is a T cell-derived cytokine that modulates T cell, B cell, and natural killer cell responses. In this study, the effects of blocking IL-21 were examined in 2 rodent models of rheumatoid arthritis (RA) to determine whether IL-21 contributes to their pathologic processes. METHODS: DBA/1 mice were immunized with bovine type II collagen and then treated with murine IL-21 receptor Fc fusion protein (IL-21R.Fc), which was initiated after the onset of arthritis symptoms in 10% of the cohort. The mice were assessed 3 times per week for signs of disease, including histologic features as well as serum cytokine, Ig, and cytokine messenger RNA (mRNA) levels in the paws. In a separate experiment, Lewis rats were immunized with Freund's complete adjuvant followed by administration of IL-21R.Fc at the peak of inflammation in the joints. Rats were assessed daily for histologic features and for scoring of arthritis severity. In addition, the effects of IL-21R.Fc on the production of interferon-gamma (IFNgamma) by T cells were examined. RESULTS: Treatment of DBA/1 mice with IL-21R.Fc reduced the clinical and histologic signs of collagen-induced arthritis. Nonspecific IgG1 levels were decreased in response to treatment. The levels of IL-6 mRNA in the paws and the serum IL-6 levels were decreased after treatment with IL-21R.Fc. IFNgamma mRNA levels were increased in the paws, and the addition of IL-21R.Fc to collagen-activated lymph node cultures enhanced the levels of IFNgamma. Collagen-specific spleen cell responses in IL-21R.Fc-treated mice were observed as reduced levels of IFNgamma and increased levels of IL-6. Treatment of Lewis rats with IL-21R.Fc after induction of adjuvant-induced arthritis resulted in reversal of disease signs and improvements in histologic parameters. CONCLUSION: These findings demonstrate a pathogenic role for IL-21 in animal models of RA, and support consideration of IL-21 as a therapeutic target in human RA.
Assuntos
Artrite Experimental/prevenção & controle , Fragmentos Fc das Imunoglobulinas/administração & dosagem , Subunidade alfa de Receptor de Interleucina-21/administração & dosagem , Interleucinas/antagonistas & inibidores , Receptores de Interleucina-21/antagonistas & inibidores , Proteínas Recombinantes de Fusão/administração & dosagem , Animais , Artrite Experimental/metabolismo , Artrite Experimental/patologia , Células Cultivadas , Citocinas/sangue , Citocinas/genética , Relação Dose-Resposta a Droga , Expressão Gênica , Subunidade alfa de Receptor de Interleucina-21/metabolismo , Interleucinas/metabolismo , Linfonodos/efeitos dos fármacos , Linfonodos/metabolismo , Ativação Linfocitária , Masculino , Camundongos , Camundongos Endogâmicos DBA , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos Lew , Ratos Sprague-Dawley , Receptores de Interleucina-21/metabolismo , Receptores do Fator de Necrose Tumoral/administração & dosagem , Receptores do Fator de Necrose Tumoral/antagonistas & inibidores , Receptores do Fator de Necrose Tumoral/genética , Baço/efeitos dos fármacos , Baço/metabolismo , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismoRESUMO
Risk factors for acute childhood diarrhea in a rural community of Chiapas, Mexico. A strategy for intervention
Assuntos
Diarreia Infantil/epidemiologia , Saúde da População Rural , Estratégias de Saúde Locais , Fatores de Risco , Doença Aguda , MéxicoRESUMO
Risk factors for acute childhood diarrhea in a rural community of Chiapas, Mexico. A strategy for intervention
