Das Ubiquitin Proteasom System generiert die Mehrheit der antigenen Peptide, die zusammen mit MHC Klasse I Molekülen präsentiert werden, wobei durch Kooperation mit alternativen proteolytischen Systemen die Vielfalt der möglichen MHC I Liganden erhöht wird. In diesem Zusammenhang, insbesondere im Rahmen einer Immunantwort, ist die Rolle von Aminopeptidasen bislang nur ungenügend charakterisiert. In der vorliegenden Arbeit wurde der modulatorische Einfluss von zytosolischen und im ER lokalisierten Aminopeptidasen auf die Generierung des HCMV pp65495-503 Epitops durch Prozessierung von proteasomal generierten Peptidprodukten untersucht. Dafür wurde in pp65 exprimierenden Zellen die Expression einzelner Aminopeptidasen mittels siRNA inhibiert und der Effekt auf die Epitoppräsentation über die Aktivierung pp65495-503 spezifischer CTL bestimmt. Es zeigte sich, dass TPPII, LAP, AP-B und POP limitierend auf die Epitoppräsentation wirken. Damit wurden die Peptidasen AP-B und POP erstmalig in direkten Zusammenhang mit der MHC Klasse I Antigenprozessierung gebracht. Analysen weiterer zytosolischer Peptidasen wie TOP, BH und PSA zeigten keinen signifikanten Effekt auf die Epitoppräsentation, so dass diese Peptidasen an der zellulären Prozessierung des pp65 Antigens nicht beteiligt sind. Die Trimmaktivität von ERAPI und ERAPII im ER hingegen hatte einen bedeutenden Anteil an der pp65495-503 Epitopgenerierung. In Immunpräzipitationsexperimenten konnte zudem die Interaktion der ER Aminopeptidasen mit dem peptide-loading complex zum ersten Mal nachgewiesen werden. Die vorliegenden Daten geben Hinweise darauf, dass die Interaktion von ERAPI und ERAPII mit dem Komplex unabhängig von dessen vollständiger Assemblierung mit dem TAP Transporter stattfinden kann und vermutlich über Tapasin vermittelt wird. Da diese Assoziation durch IFNgamma induziert wird, könnte sie zu einer effizienteren Antigenprozessierung und -Präsentation, vor allem unter Infektionsbedingungen, beitragen. / The ubiquitin proteasome system is responsible for the generation of the majority of MHC class I presented antigenic peptides. By cooperation with alternative proteolytic systems the diversity of MHC class I ligands is increased. In this context, especially during immune response, the role of aminopeptidases is barely characterised. In this project the effect of cytosolic and ER-resident aminopeptidases on processing of proteasomal generated peptides was investigated with regard to HCMV pp65495-503 epitope generation. Therefore, expression level of single aminopeptidases was down regulated by siRNA in pp65 expressing cells and the effect of down regulation on epitope presentation was analysed by activation of pp65495-503 specific CTLs. It could be demonstrated that TPPII, LAP, AP-B and POP have negative effects on pp65 epitope presentation. With AP-B and POP two additional cytosolic aminopeptidases with a functional role in epitope processing were identified. Other aminopeptidases, that have been characterised as part of the antigen processing machinery, namely TOP, BH and PSA, did not affect pp65 epitope generation. In contrast, trimming by ERAPI and ERAPII in the ER resulted in an efficient epitope presentation. For the first time, experimental evidence was provided that the two ER-resident peptidases interact with the MHC class I peptide-loading complex (PLC). The obtained results indicate that this association takes place independently of the assembly of the entire complex including TAP and is probably mediated by tapasin. The observation that this complex formation is inducible by IFNgamma suggests that the association of ERAPI and ERAPII to the PLC accounts for a better antigen processing and presentation mainly at the site of infection.

Introdução. Nas últimas décadas o transplante renal se tornou a melhor opção terapêutica para a doença renal crônica terminal, oferecendo melhora na sobrevida e na qualidade de vida dos pacientes. No entanto, o uso obrigatório de medicamentos imunossupressores predispõe a uma variedade de episódios infecciosos, incluindo, entre as mais importantes, a infecção por citomegalovírus. O objetivo deste estudo é avaliar os métodos diagnósticos para infecção ativa por Citomegalovírus, a antigenemia pp65 e a PCR qualitativa, identificando assim a melhor correlação clinicolaboratorial. Métodos. Estudo de coorte prospectiva, desenvolvido no Serviço de Nefrologia do Hospital de Clínicas de Porto Alegre (HCPA) utilizando-se amostras de pacientes submetidos a transplante renal no HCPA. A monitorização de infecção por Citomegalovírus foi realizada pelos testes da antigenemia PP-65, PCR qualitativo e PCR quantitativo. Resultados. Antigenemia pp-65 mostrou-se mais útil na monitorização de infecção ativa por citomegalovírus do que PCR qualitativa. Houve correlação significativa entre o desenvolvimento de infecção ativa diagnosticada por antigenemia pp-65 e transplantes realizados entre doador e receptor com sorologia IgG específica para Citomegalovírus positiva, terapia de indução com anticorpos anti-receptor de Interleucina-2 e o uso de terapia profilática e entre infecção ativa diagnosticada por PCR qualitativa e sorologias positivas do doador e do receptor e com uso de profilaxia. Conclusão. Ambos os métodos são úteis para diagnóstico da infecção ativa por CMV. No entanto, mais estudos são necessários para estabelecer a melhor correlação clínico-laboratorial em pacientes transplantados renais. A quantificação do DNA viral através dos métodos de PCR quantitativa pode oferecer alternativa útil neste sentido. / Background. In the last decades renal transplantation has became the most effective therapy for end-stage renal diseases offering better survival and quality of life. However, the use of immunosuppressive agents may predispose to a variety of infections including, among the most important, cytomegalovirus infection. The objective of the present study is to evaluate pp65 cytomegalovirus antigenemia and qualitative PCR as diagnostic methods for active CMV disease. Methods. This is a prospective cohort study enrolling patients that received a kidney transplant at Hospital de Clínicas de Porto Alegre who where monitored for CMV active infection with pp65 cytomegalovirus antigenemia and qualitative PCR over the post-transplant follow-up. Results. The use of pp65 antigenemia is a more useful method for the diagnosis of active CMV disease. A positive correlation was found between active infection as measured by pp65 cytomegalovirus antigenemia and pre-transplant IgG CMV serology, induction therapy, use of IL-2 receptor antibodies, gancyclovir prophylaxis. PCR diagnosis correlated with donor and recipient CMV IgG serology and gancyclovir prophylaxis. Conclusions. Both methods are useful for the diagnosis of active CMV disease. However, more studies seems to be necessary to establish the best clinical and laboratory correlation. Quantitative CMV PCR may offer a useful alternative in this clinical scenario.

Introdução. Nas últimas décadas o transplante renal se tornou a melhor opção terapêutica para a doença renal crônica terminal, oferecendo melhora na sobrevida e na qualidade de vida dos pacientes. No entanto, o uso obrigatório de medicamentos imunossupressores predispõe a uma variedade de episódios infecciosos, incluindo, entre as mais importantes, a infecção por citomegalovírus. O objetivo deste estudo é avaliar os métodos diagnósticos para infecção ativa por Citomegalovírus, a antigenemia pp65 e a PCR qualitativa, identificando assim a melhor correlação clinicolaboratorial. Métodos. Estudo de coorte prospectiva, desenvolvido no Serviço de Nefrologia do Hospital de Clínicas de Porto Alegre (HCPA) utilizando-se amostras de pacientes submetidos a transplante renal no HCPA. A monitorização de infecção por Citomegalovírus foi realizada pelos testes da antigenemia PP-65, PCR qualitativo e PCR quantitativo. Resultados. Antigenemia pp-65 mostrou-se mais útil na monitorização de infecção ativa por citomegalovírus do que PCR qualitativa. Houve correlação significativa entre o desenvolvimento de infecção ativa diagnosticada por antigenemia pp-65 e transplantes realizados entre doador e receptor com sorologia IgG específica para Citomegalovírus positiva, terapia de indução com anticorpos anti-receptor de Interleucina-2 e o uso de terapia profilática e entre infecção ativa diagnosticada por PCR qualitativa e sorologias positivas do doador e do receptor e com uso de profilaxia. Conclusão. Ambos os métodos são úteis para diagnóstico da infecção ativa por CMV. No entanto, mais estudos são necessários para estabelecer a melhor correlação clínico-laboratorial em pacientes transplantados renais. A quantificação do DNA viral através dos métodos de PCR quantitativa pode oferecer alternativa útil neste sentido. / Background. In the last decades renal transplantation has became the most effective therapy for end-stage renal diseases offering better survival and quality of life. However, the use of immunosuppressive agents may predispose to a variety of infections including, among the most important, cytomegalovirus infection. The objective of the present study is to evaluate pp65 cytomegalovirus antigenemia and qualitative PCR as diagnostic methods for active CMV disease. Methods. This is a prospective cohort study enrolling patients that received a kidney transplant at Hospital de Clínicas de Porto Alegre who where monitored for CMV active infection with pp65 cytomegalovirus antigenemia and qualitative PCR over the post-transplant follow-up. Results. The use of pp65 antigenemia is a more useful method for the diagnosis of active CMV disease. A positive correlation was found between active infection as measured by pp65 cytomegalovirus antigenemia and pre-transplant IgG CMV serology, induction therapy, use of IL-2 receptor antibodies, gancyclovir prophylaxis. PCR diagnosis correlated with donor and recipient CMV IgG serology and gancyclovir prophylaxis. Conclusions. Both methods are useful for the diagnosis of active CMV disease. However, more studies seems to be necessary to establish the best clinical and laboratory correlation. Quantitative CMV PCR may offer a useful alternative in this clinical scenario.

Introdução. Nas últimas décadas o transplante renal se tornou a melhor opção terapêutica para a doença renal crônica terminal, oferecendo melhora na sobrevida e na qualidade de vida dos pacientes. No entanto, o uso obrigatório de medicamentos imunossupressores predispõe a uma variedade de episódios infecciosos, incluindo, entre as mais importantes, a infecção por citomegalovírus. O objetivo deste estudo é avaliar os métodos diagnósticos para infecção ativa por Citomegalovírus, a antigenemia pp65 e a PCR qualitativa, identificando assim a melhor correlação clinicolaboratorial. Métodos. Estudo de coorte prospectiva, desenvolvido no Serviço de Nefrologia do Hospital de Clínicas de Porto Alegre (HCPA) utilizando-se amostras de pacientes submetidos a transplante renal no HCPA. A monitorização de infecção por Citomegalovírus foi realizada pelos testes da antigenemia PP-65, PCR qualitativo e PCR quantitativo. Resultados. Antigenemia pp-65 mostrou-se mais útil na monitorização de infecção ativa por citomegalovírus do que PCR qualitativa. Houve correlação significativa entre o desenvolvimento de infecção ativa diagnosticada por antigenemia pp-65 e transplantes realizados entre doador e receptor com sorologia IgG específica para Citomegalovírus positiva, terapia de indução com anticorpos anti-receptor de Interleucina-2 e o uso de terapia profilática e entre infecção ativa diagnosticada por PCR qualitativa e sorologias positivas do doador e do receptor e com uso de profilaxia. Conclusão. Ambos os métodos são úteis para diagnóstico da infecção ativa por CMV. No entanto, mais estudos são necessários para estabelecer a melhor correlação clínico-laboratorial em pacientes transplantados renais. A quantificação do DNA viral através dos métodos de PCR quantitativa pode oferecer alternativa útil neste sentido. / Background. In the last decades renal transplantation has became the most effective therapy for end-stage renal diseases offering better survival and quality of life. However, the use of immunosuppressive agents may predispose to a variety of infections including, among the most important, cytomegalovirus infection. The objective of the present study is to evaluate pp65 cytomegalovirus antigenemia and qualitative PCR as diagnostic methods for active CMV disease. Methods. This is a prospective cohort study enrolling patients that received a kidney transplant at Hospital de Clínicas de Porto Alegre who where monitored for CMV active infection with pp65 cytomegalovirus antigenemia and qualitative PCR over the post-transplant follow-up. Results. The use of pp65 antigenemia is a more useful method for the diagnosis of active CMV disease. A positive correlation was found between active infection as measured by pp65 cytomegalovirus antigenemia and pre-transplant IgG CMV serology, induction therapy, use of IL-2 receptor antibodies, gancyclovir prophylaxis. PCR diagnosis correlated with donor and recipient CMV IgG serology and gancyclovir prophylaxis. Conclusions. Both methods are useful for the diagnosis of active CMV disease. However, more studies seems to be necessary to establish the best clinical and laboratory correlation. Quantitative CMV PCR may offer a useful alternative in this clinical scenario.

<p>The main focus of my thesis has been to develop protocols for generating antigen-specific cytotoxic T lymphocytes (CTLs) and T helper cells (T_H) for adoptive transfer to treat cytomegalovirus (CMV) disease and prostate cancer. CMV viremia is a severe complication in immunocompromised stem cell transplanted patients. Prostate cancer is a leading cause of death for men in Western countries. Although different in nature, CMV-infected cells and prostate cancer cells can both be eliminated through specific activation of the adaptive immune system. </p><p>To generate CMV pp65-specific T cells, I utilized dendritic cells (DCs) modified with an HLA-A*0201/pp65_495-503 peptide, a recombinant adenovirus coding for pp65, <i>in vitro</i> transcribed pp65 mRNA and a recombinant pp65 protein. Peptide stimulation yielded large numbers of peptide-specific CD8⁺ T cells with high lytic activity while adenovirus or mRNA stimulation resulted in the expansion of CTLs against multiple pp65 epitopes. The recombinant protein activated primarily CD4⁺ T_H cells. Stimulation with DCs co-modified with pp65 mRNA and pp65 protein simultaneously generated both pp65-specific CTLs and T_H cells. Such T cells would cover all pp65 epitopes while avoiding potential virus related biohazards. The mRNA/protein combinatory approach can be used to stimulate T cells <i>ex vivo</i> from virtually all stem cell donors for adoptive T cell transfer. </p><p>I have identified two immunogenic HLA-A*0201-restricted peptide epitopes from the prostate tissue antigen TARP. Repeated stimulations with TARP peptide-pulsed DCs yielded up to 20% TARP-directed CD8⁺ T cells even when starting from undetectable frequencies (<0.01%). The T cells could be sorted to 99% purity and expanded 1000-fold with retained specificity and activity. We also detected TARP-directed CD8⁺ T cells in the blood of prostate cancer patients. Therefore, TARP seems to have potential as antigen in DC vaccination or adoptive T cell therapy of prostate cancer. </p>

The main focus of my thesis has been to develop protocols for generating antigen-specific cytotoxic T lymphocytes (CTLs) and T helper cells (TH) for adoptive transfer to treat cytomegalovirus (CMV) disease and prostate cancer. CMV viremia is a severe complication in immunocompromised stem cell transplanted patients. Prostate cancer is a leading cause of death for men in Western countries. Although different in nature, CMV-infected cells and prostate cancer cells can both be eliminated through specific activation of the adaptive immune system. To generate CMV pp65-specific T cells, I utilized dendritic cells (DCs) modified with an HLA-A*0201/pp65495-503 peptide, a recombinant adenovirus coding for pp65, in vitro transcribed pp65 mRNA and a recombinant pp65 protein. Peptide stimulation yielded large numbers of peptide-specific CD8+ T cells with high lytic activity while adenovirus or mRNA stimulation resulted in the expansion of CTLs against multiple pp65 epitopes. The recombinant protein activated primarily CD4+ TH cells. Stimulation with DCs co-modified with pp65 mRNA and pp65 protein simultaneously generated both pp65-specific CTLs and TH cells. Such T cells would cover all pp65 epitopes while avoiding potential virus related biohazards. The mRNA/protein combinatory approach can be used to stimulate T cells ex vivo from virtually all stem cell donors for adoptive T cell transfer. I have identified two immunogenic HLA-A*0201-restricted peptide epitopes from the prostate tissue antigen TARP. Repeated stimulations with TARP peptide-pulsed DCs yielded up to 20% TARP-directed CD8+ T cells even when starting from undetectable frequencies (&lt;0.01%). The T cells could be sorted to 99% purity and expanded 1000-fold with retained specificity and activity. We also detected TARP-directed CD8+ T cells in the blood of prostate cancer patients. Therefore, TARP seems to have potential as antigen in DC vaccination or adoptive T cell therapy of prostate cancer.