Inducción de tolerancia en modelo de autotrasplante / Induction of tolerance in allogeneic transplant model

Introduction: Vascularized composite allotransplantation (VCA) involves the transplantation of complex anatomical structures including different kinds of tissue. The aim was to study the effect of a treatment with immature dendritic cells in a model of VCA. Materials and Methods: The rat hind limb allotransplantation model was used. Due to the high antigenic mistmatch Brown Norway rats were used as donors and Lewis rats as recipients. The bone marrow derived immature dendritic cells were cultured under GM-CSF stimuli and donor tissue. The rejection grade and the survival of the graft were assessed. Experimental groups: group I (n = 3): no treatment; Group II (n = 6): tacrolimus 10 mg/kg one day before the transplantation (day -1); Group III (n = 3): tacrolimus 10 mg/kg on day -1 and 6 mg/kg from day 0 to 14, plus intravenous saline infusion on days 7 and 14; Group IV (n = 3): tacrolimus 10 mg/kg on day -1 and 6 mg/kg from day 0 to 14, plus intravenous immature dendritic cells on days 7 and 14. Results: All 15 allografts developed rejection. The mean allograft survival was 14 days in group I, 15 days in group II, 34 days in group III and 58 days in groups IV (p < 0.05). Conclusions: In the rat hind limb allotransplantation model under tacrolimus monotherapy, the treatment with immature bone marrow derived dendritic cells pulsed with alloantigens increases the survival of the graft.

Introducción: El alotrasplante compuesto vascularizado (ACV) involucra el trasplante de estructuras anatómicas complejas que pueden contener distintos tipos de tejidos. El objetivo de este estudio fue evaluar el efecto del tratamiento con células dendríticas inmaduras derivadas de médula ósea del receptor y cargadas con aloantígenos como potencial inductor de tolerancia en un modelo de ACV. Animales y Métodos: Para realizar el modelo de alotrasplante de extremidad posterior de la rata, se utilizaron como donantes ratas Brown Norway y como receptoras ratas Lewis. Las células dendríticas se diferenciaron a partir de precursores de médula ósea que se cargaron con lisado de tejido del donante. Grupos experimentales: Grupo I (n = 3): sin tratamiento; Grupo II (n = 6): tacrolimus 10 mg/kg vía oral el día previo al trasplante (día -1); Grupo III (n = 3): tacrolimus 10 mg/kg el día -1 y 6 mg/kg desde el día 0 al 14 post operatorio como mantención; Grupo IV (n = 3): mismo esquema de tacrolimus que grupo III, pero además infusión intravenosa de células dendríticas los días 7 y 14. Se evaluó la sobrevida de los implantes y el grado de rechazo. Resultados: Los 15 animales trasplantados presentaron rechazo. La sobrevida media del ACV fue de 14 días en el grupo I, 15 días en el grupo II, 34 días en el grupo III y 58 días en el grupo IV (p < 0,05). Conclusión: En un modelo de ACV bajo tratamiento con tacrolimus, la infusión de células dendríticas inmaduras derivadas de médula ósea y pulsadas con aloantígeno aumentan la sobrevida del implante.

Antígenos leucocitarios humanos y su asociación con resistencia/susceptibilidad a la infección por el VIH-1 / Human leukocyte antigens associated to resistance/susceptibility to HIV infection

El curso clínico de la infección por el virus de inmunodeficiencia humana tipo 1 es un proceso variable y complejo que depende de componentes virales y del hospedero. En la mayoría de los individuos infectados, la respuesta inmune generada en las fases iniciales de la infección logra controlar la replicación viral por mecanismos efectores innatos, de anticuerpos neutralizantes específicos y particularmente de la actividad de los linfocitos T CD8+ (LT CD8+). A pesar de generarse una respuesta inmune específica, esta se vuelve ineficaz en las etapas crónicas de la infección debido a cambios en los péptidos virales blanco, los cuales conducen a una pérdida del reconocimiento del antígeno presentado; dichos cambios son dados por la baja fidelidad de la transcriptasa reversa y la selección de cuasi-especies por la presión inmunológica. Durante la activación de los LT CD8+ es importante la señal ejercida por el péptido viral, el cual se presenta en el contexto de una molécula del complejo mayor de histocompatibilidad clase I (CMH-I). Estudios de correlación entre el CMH-I y la resistencia/susceptibilidad (R/S) al VIH se han centrado en cuatro aspectos: 1) la expresión de alelos específicos; 2) el grado de homocigocidad/heterocigocidad; 3) la exposición a diversos aloantígenos; 4) la relación con receptores KIR. En esta revisión se aborda el fenómeno de resistencia/susceptibilidad a la infección por el VIH-I relacionado con el CMH-I, cuyo entendimiento favorecerá el desarrollo de herramientas novedosas de intervención terapéutica.

The clinical course of infection with human immunodeficiency virus type-1 (HIV-1) is a variable and complex process that depends on viral and host components. In the majority of infected individuals, the immune response is generated from the initial phases of infection, achieving the control of the viral replication through innate effector mechanisms, neutralizing specific antibodies and particularly through cytotoxic CD8+T cell activity. Despite the generation of these specific cellular and humoral responses, it becomes ineffective in chronic stages of infection because of changes in viral peptide targets, the low fidelity of the reverse transcriptase and the immune pressure. During the activation of CD8+ T cells, the signal delivered by the viral peptide presented in the context of the class I major histocompatibility complex (MHC-I) molecules, is essential. Correlation studies between the MHC-I and the resistance/ susceptibility (R/S) to HIV infection have focused on four aspects, namely: 1) the expression of specific alleles; 4) the degree of homozygosity/heterozygosity; 3) the degree of exposure to different alloantigens; 4) the relation with KIR receptors. In this review, we focus on resistance/susceptibility to HIV-1 infection, particularly related to the MHC, hoping to have a better understanding of this phenomenon that may allow the development of novel therapeutic intervention tools.

Differential expression of genes in dendritic cell induced by human alloantigens and cytomegalovirus antigen / 白血病·淋巴瘤

[Objective]To investigate differential gene expression in dendritic cell(DC) in response to human alloantigen and cytomegalovirus protein,and search target genes which can prevent graft rejection and eytomegalovirus (CMV) infection.[Methods]Genome-wide microarray analysis was performed to test gene expression in DC in response to human alloantigen and cytomegalovirus protein 3A(CMV3A).[Results]The Results showed that the difference of gene expression of DC induced by CMV3A and alloantigen was significant.The genes with differential expression included antigen processing and presentation,toll-like receptor signaling pathway and cell movement/migration, cytokine-cytokine receptor interaction and metabolism of xenobiotics by cytochrome p450,and several heat shock protein(HSP) family members including HSPA5,HSPA8,HSPA9B and HSP90AB1,in DC induced hy alloantigen were higher expression than that by CMV3A.[Conclusion]This study found several genes including heat shock protein family in DC induced by alloantigen were higher expression than that by CMV3A,these genes might play a valuable role in preventing graft rejection and CMV infection.

Avaliação clínica, histológica e imunológica de enxertos ósseos alógenos fresco-congelados utilizados como técnica na preservação de rebordo alveolar pós-extração / Preservation of alveolar bone in extraction sockets using fresh-frozen bone allograft: a clinical, histological and immunological study

O osso alógeno fresco-congelado (FFBA, do inglês fresh-frozen bone allograft) é uma alternativa para os procedimentos cirúrgicos de enxerto ósseo, principalmente na preparação do rebordo alveolar para a instalação de implantes osseointegráveis. No entanto, existem alguns paradigmas que envolvem a relação entre resposta do sistema imunológico à aloantígenos presentes no enxerto e o seu comportamento clínico. Procurando entender essa relação, o FFBA foi avaliado como enxerto para preservar o rebordo alveolar pós-extração. Os resultados mostraram que embora tenha ocorrido uma redução estatisticamente significante na altura, espessura e volume do rebordo entre a avaliação inicial e final, essa redução não foi clinicamente significante, permitindo a instalação de implantes osseointegráveis. Em adição, as análises histológicas sugerem um bom comportamento do enxerto, com ausência de reação do tipo corpo estranho e formação de novo osso em todos os sítios analisados. Ao analisar o comportamento da resposta imune, os resultados mostraram que a injeção intradérmica de aloantígenos presentes no FFBA, não induziu uma reação de hipersensibilidade tardia nos pacientes após 4 meses do enxerto. Além disso, os monócitos do sangue periférico (PBMCs) dos pacientes não proliferaram frente aos aloantígenos in vitro. No entanto, os dados também demonstraram que os aloantígenos aumentam a produção de IL-2 e IFN-, mas não alteram a produção de IL-4 e IL-10, por PBMCs dos pacientes. Ao avaliar a relação entre a produção dessas citocinas e o comportamento clínico do enxerto, os dados mostram que existe uma correlação estatisticamente significante entre a produção de IL-2 in vitro e a redução (em %) da altura do rebordo alveolar, embora essa redução não tenha sido clinicamente significante. De fato, a presença de aloantígenos no FFBA não é suficiente para sua contraindicação como material de enxertia.

The fresh-frozen bone allograft (FFBA) is an alternative to surgical procedures of bone grafts, mainly in the preservation of alveolar ridge prior the installation of osseointegrated implants. However there are paradigms that surround the relation between immune response to alloantigens present inside the graft and the clinical response of the graft. An attempt to understand this relationship, the FFBA was evaluated as a graft to preserve the alveolar ridge post-extraction. The results show a statistically significant reduction in height, thickness and volume of the ridge between the initial and final examination, however this reduction was not clinically significant. The ridge preservation allowed implant installation and osseointegration. In addition, histologic analysis suggests a good performance of the graft with no foreign body reaction and formation of new bone at all sites. In analyzing the behavior immune response, the results showed that stimulation with alloantigens present in bone allograft induced no delayed hypersensitivity reaction in vivo. Additionally, periphery blood mononuclear cells (PBMC) from patients no proliferate in response to alloantigens in vitro. However, the data also demonstrated that the alloantigens increase IL-2 and IFN- production, but no IL-4 and IL-10 production, by PBMCs from patients. When evaluate the relation between the cytokines production and clinical parameters, the results demonstrate that there statistically significant correlation between IL-2 production in vitro and ridge height changes (%), although this clinical parameter is not clinically significant. In fact, the alloantigens in FFBA are not sufficient for its contraindications as grafting material.