RESUMO
Listeriolysin O (LLO) has been proposed as a potential carrier or adjuvant molecule in the vaccination field. However, the cytotoxic and pro-apoptotic effects of LLO are the major limitations for this purpose. Here, we have performed a preclinical safety evaluation and characterized a new potential adjuvant application for a non-cytolytic LLO mutant (dtLLO) to enhance and modulate the immune response against the envelope (E) protein from dengue virus. In addition, we have studied the adjuvant effects of dtLLO on human immune cells and the role of membrane cholesterol for the binding and proinflammatory property of the toxoid. Our in-vivo results in the murine model confirmed that dtLLO is a safer molecule than wild-type LLO (wtLLO), with a significantly increased survival rate for mice challenged with dtLLO compared with mice challenged with wtLLO (P < 0·001). Histopathological analysis showed non-toxic effects in key target organs such as brain, heart, liver, spleen, kidney and lung after challenge with dtLLO. In vitro, dtLLO retained the capacity of binding to plasma membrane cholesterol on the surface of murine and human immune cells. Immunization of 6-8-week-old female BALB/c mice with a combination of dtLLO mixed with E protein elicited a robust specific humoral response with isotype diversification of immunoglobulin (Ig)G antibodies (IgG1 and IgG2a). Finally, we demonstrated that cholesterol and lipid raft integrity are required to induce a proinflammatory response by human cells. Taken together, these findings support a potential use of the dtLLO mutant as a safe and effective adjuvant molecule in vaccination.
Assuntos
Adjuvantes Imunológicos , Antígenos Virais/imunologia , Toxinas Bacterianas/imunologia , Vírus da Dengue/imunologia , Proteínas de Choque Térmico/imunologia , Proteínas Hemolisinas/imunologia , Imunidade Humoral , Proteínas Mutantes/imunologia , Animais , Anticorpos Antivirais/imunologia , Especificidade de Anticorpos/imunologia , Toxinas Bacterianas/genética , Colesterol/metabolismo , Citocinas/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Dengue/imunologia , Dengue/patologia , Dengue/prevenção & controle , Modelos Animais de Doenças , Feminino , Proteínas de Choque Térmico/genética , Proteínas Hemolisinas/genética , Hemólise/imunologia , Imunização , Mediadores da Inflamação/metabolismo , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Lipídeos de Membrana/metabolismo , Camundongos , Proteínas Mutantes/genética , Ligação Proteica/imunologiaRESUMO
No se han descubierto evidencias consistentes a favor de las reglas de valoración clínica del ABCD y de los 7 puntos, como herramientas útiles para decidir si se debe hacer una biopsia de lesiones compatibles con nevus o melanoma (AU)
