Submitted by Diogo Misoguti (diogo.misoguti@gmail.com) on 2016-07-08T18:20:15Z No. of bitstreams: 1 cp124617.pdf: 1851616 bytes, checksum: 98299c340bd6b09b83e3fdf34f6adcf5 (MD5) / Approved for entry into archive by Diogo Misoguti (diogo.misoguti@gmail.com) on 2016-07-08T18:20:49Z (GMT) No. of bitstreams: 1 cp124617.pdf: 1851616 bytes, checksum: 98299c340bd6b09b83e3fdf34f6adcf5 (MD5) / Made available in DSpace on 2016-07-08T18:20:49Z (GMT). No. of bitstreams: 1 cp124617.pdf: 1851616 bytes, checksum: 98299c340bd6b09b83e3fdf34f6adcf5 (MD5) Previous issue date: 2009 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Associação Fundo de Incentivo à Psicofarmacologia (AFIP) / Introdução: Transplante alogênico de células tronco hematopoéticas (TCTH) é uma importante terapia para doenças hematológicas, mas o sucesso de uma porção de transplantes é limitado pela doença do enxerto versus hospedeiro(GVHD). Os fatores de risco conhecidos para GVHD agudo (aGVHD) não fornecem uma estimativa precisa do risco individual e não auxiliam na individualização da terapia. Até o momento, não existe método diagnóstico que permita predizer aGVHD. A identificação de pacientes que desenvolverão aGVHD poderia permitir a individualização da terapia para uns e evitaria imunossupressão intensa para outros. Objetivos: Revelar um classificador molecular preditivo de aGVHD. Descobrir genes diferencialmente expressos e analisar eventos precoces que desencadeiam aGVHD. Explorar categorias funcionais e tipos celulares relacionados ao desenvolvimento de aGVHD. Casuística e métodos: Foram isolados, amplificados, marcados e co-hidridados com lâminas de microarray contendo 22.000 sondas, amostras de RNA mensageiro de 89 pacientes submetidos a TCTH HLA-idêntico mieloablativo ou de toxicidade reduzida, obtido de células mononucleares periféricas durante a enxertia medular. Os pacientes foram divididos em grupo treino e grupo teste, um modo utilizado para construir um modelo que discrimine pacientes com e sem aGVHD, e para testar o modelo em amostras independentes. Os genes informativos foram selecionados utilizando recursive feature elimination, seguido de sete diferentes algoritmos de classificação multivariados para estabelecer o classificador molecular no grupo treino. Os genes diferencialmente expressos entre amostras de pacientes com e sem GVHD foram submetidos a análise de enriquecimento das vias funcionais e agrupados de acordo com o perfil de expressão com células e tecidos através do SymAtlas. Resultados: Encontramos um classificador molecular composto de 233 genes nas amostras do grupo treino, que foram selecionados baseados na mais precisa classificação. No grupo teste da amostra, cerca de 80% dos pacientes puderam ser classificados. Para estes pacientes, o classificador mostrou uma acurácia preditiva de 75% (sensibilidade de 71% e especificidade de 78%). Analisando a anotação funcional dos genes diferencialmente expressos, observamos que em pacientes que desenvolveram aGVHD, houve aumento de expressao de genes da resposta antimicrobiana, transporte de gases, metabolismo de hemoglobina, além das alarminas. Nestas amostras também observamos a diminuição da expressão da IL1 e outros genes envolvidos na via do NF-kB. Vários genes super-expressos no periodo precoce do aGVHD foram associados a células precursoras. Conclusões: Nossos resultados mostram que um classificador molecular é capaz de identificar pacientes sob alto risco de desenvolver aGVHD. Estabelecer métodos de diagnóstico preditivo para aGVHD é o primeiro passo para a individualização da estratégia terapêutica após TCTH. Além disso, os resultados da análise de enriquecimento funcional e a expressão de genes em diferentes populações celulares, sugerem que eventos precoces envolvendo múltiplas populações de células precursoras possam predefinir a interação futura entre o enxerto em desenvolvimento e o paciente. / Background: Allogeneic hematopoietic stem cell transplantation is an important last resort therapy for hematological diseases. Unfortunately, the success of a large proportion of these transplants is limited by graft-versus-host disease (GVHD). Currently known risk factors for acute GVHD (histoincompatibility, sex mismatch, older patients, previous pregnancies) do not provide a precise estimate of individual patient risk and do not help for individualization of the therapy. Early identification of those patients who will develop aGVHD may allow for individualized treatment, and also for the reduction of unnecessary treatment for those patients not at risk. Nowadays, however, there is no diagnostic method that allows prediction of aGVHD. Objectives: The goal of our study was to reveal a gene expression profile that would predict the occurrence of aGVHD. In addition, using enrichment of gene ontology categories, to analyze differentially expressed genes in order to better understand biology of the events preceding aGVHD. Material and methods: we collected blood samples from 89 recipients of myeloablative and reduced conditioning regimen HLA-identical sibling allogeneic hematopoietic stem cell transplants at the time of successful engraftment. We isolated total RNA from the peripheral blood mononuclear cells, amplified it, labeled, and co-hybridized to the microarray slides containing probes for 22,000 genes..The patients were divided into training and test groups, the former used to build a model discriminating patients with and without aGVHD and the latter - to test the model on independent samples. We selected the informative genes using “recursive feature elimination” method followed by seven different multivariate classification algorithms in order to establish a molecular classifier in the training set. Then we validated this new classifier in the test set of patients.. We found differentially expressed genes using T-test and accepted those with estimated false discovery rate below 10%. We have used Biobase Explain to find enrichment of functional groups among differentially expressed genes.Results: We found a molecular classifier comprised by 233 gene probes in the training set of samples which were selected based on the most accurate classification. In the test group of samples, we found that 80% of patients could be classified based on the concordance between classification methods as described above. For these patients, the classifier showed 75% of a predictive accuracy (71% of sensitivity and 78% of specificity). Analysis of functional annotations of differentially expressed genes showed that patients that developed acute GVHD have increased expression of antimicrobial genes, hemaglobin metabolism genes and alarmins. In these samples we also observed decreased expression of IL-1 and other genes involved in NF-kB activation. Several genes up-regulated before aGVHD were associated with multiple types of precursor cells. Conclusion: Our results show that molecular profiling is able to identify patients under high risk of acute GVHD at the time of engraftment. Establishing of a predictive diagnostic method for aGVHD is the first step of individualization of therapeutic strategy after hematopoetic stem cell transplantation. In addition, the results of functional enrichment analysis and expression in different cell populations suggest that early events during engrafment involving precursor cell populations might predefine results of interaction between stem cell allograft and patient body.

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La leucémie lymphoblastique aiguë (LLA) est le cancer le plus fréquent chez les enfants. Malgré le fait que plus de 80% des enfants atteints de LLA sont aujourd'hui guéris de leur maladie, ce succès a toutefois un prix élevé, car l’exposition aux médicaments cytotoxique et/ou à l’irradiation pendant une période vulnérable du développement de l’enfant peut entraîner des conséquences à long terme. En effet, environ 60% des enfants ayant survécu à une LLA devront vivre avec des problèmes de santé liés au traitement, également appelés effets indésirables tardifs (late-adverse effects, LAEs). Parmi ces derniers, on notera des problèmes métaboliques, l’ostéoporose, une altération des fonctions cognitives ou cardiaques, ainsi que la dépression et l’anxiété. Si certains survivants ne présentent aucune de ces complications, d'autres peuvent en avoir plusieurs. Différents facteurs peuvent contribuer à cette variabilité, notamment le traitement reçu, les caractéristiques de la maladie, les habitudes de vie et, surtout, la constitution génétique du patient. Ce projet s'est concentré sur les biomarqueurs génétiques permettant d'identifier les individus les plus susceptibles de souffrir de LAEs. Récemment, une étude exhaustive (évaluations cliniques, psychosociales et biochimiques) s’est déroulée au CHU Sainte-Justine pour caractériser chacune de ces morbidités chez 250 survivants de la LLA de l'enfant (cohorte PETALE). De plus, on a obtenu le profil génétique de chaque participant. Nous avons utilisé cet ensemble de données et des outils statistiques et bio-informatiques pour réaliser des études d'association comparant la fréquence des variants génétiques chez les survivants ayant développé ou non des LAEs; en particulier, les complications cardiovasculaires et neurocognitives, ainsi que les troubles de l'humeur tels que l'anxiété et la dépression. D'autres facteurs de risque tels que les caractéristiques de traitement et/ou de la leucémie ont été pris en compte lors de l'analyse pour dériver les meilleurs prédicteurs génétiques. Ainsi, en utilisant l'approche des gènes candidats, nous avons identifié les variants communs des gènes MTR, PPARA, ABCC3, CALML5, CACNB2 et PCDHB10 qui étaient associés à des déficits de performance des tests neurocognitifs, tandis que les variants des gènes SLCO1B1 et EPHA5 étaient associés à l'anxiété et à la dépression. Deux variants, rs1805087 dans le gène MTR et rs58225473 dans le gène CACNB2 sont particulièrement intéressants, car ces associations ont été validées dans la cohorte de réplication SJLIFE (St. Jude Children's Research Hospital, Memphis, USA). Les analyses d'association ont été complémentées par une étude d'association à l'échelle de l'exome, qui a identifié plusieurs gènes supplémentaires comme des modulateurs potentiels du risque de développer des complications neurocognitives liées au traitement (gènes AK8 et ZNF382), ainsi que l'anxiété et la dépression (gènes PTPRZ1, MUC16, TNRC6C-AS1, APOL2, C6orf165, EXO5, CYP2W1 et PCMTD1). Le variant rs61732180 du gène ZNF382 a ensuite été validé dans la cohorte de réplication SJLIFE. Également, nous avons effectué des analyses d’association concernant les complications cardiaques liées au traitement qui ont identifié plusieurs nouveaux marqueurs associés à ces complications dans les gènes TTN, NOS1, ABCG2, CBR1, ABCC5, AKR1C3, NOD2 et ZNF267. De plus, nous avons résumé les connaissances actuelles sur les marqueurs pharmacogénomiques qui ont été associés aux effets de cardiotoxicités, induites par les anthracyclines, qui affectent les patients atteints de cancer pédiatrique. Nous avons également inclus un aperçu de l'applicabilité des résultats rapportés, notamment ceux qui ont été validés dans la cohorte PETALE. Par ailleurs, nous nous sommes intéressés aux complications qui surviennent après une greffe de cellules souches hématopoïétiques. Nous avons appliqué des approches bio-informatiques et statistiques similaires pour obtenir un profil plus complet de la composante génétique derrière ces complications potentiellement mortelles. Ainsi, une étude d'association à l'échelle de l'exome a été réalisée dans une cohorte de patients pédiatriques subissant une greffe de cellules souches hématopoïétiques après un régime de conditionnement contenant du busulfan. Nous avons identifié de nouvelles variations génétiques conférant un risque plus élevé de syndrome d'obstruction sinusoïdale (notamment dans les gènes UGT2B10, BHLHE22, et KIAA1715) et de maladie aiguë du greffon contre l'hôte (dans les gènes ERC1, PLEK, NOP9 et SPRED1), qui pourraient être utiles pour des stratégies personnalisées de prévention et de traitement. Ces travaux contribuent à la compréhension de l'influence des facteurs génétiques sur le risque de développer des complications liées au traitement, tant au cours du traitement qu'à long terme. De plus, les marqueurs génétiques signalés ainsi que d'autres facteurs de risque connus peuvent conduire à des modèles de prédiction identifiant les patients à risque accru de ces complications. / Acute lymphoblastic leukemia (ALL) is the most common cancer in children. Even though more than 80% of children with ALL are now cured of their disease, this success comes at a high price as exposure to cytotoxic drugs and/or radiation during a vulnerable period of child development may have long-term consequences. In fact, approximately 60% of children who survive ALL will have to live with treatment-related health problems, also called late-adverse effects (LAEs). These include metabolic problems, osteoporosis, impaired cardiac or cognitive functions, as well as depression and anxiety. While some survivors do not have any of these complications, others may have more than one. Different factors can contribute to this variability, in particular, the treatment received, the characteristics of the disease, the lifestyle, and, above all, the genetic makeup of the patient. This project focused on genetic biomarkers capable of identifying the individuals most likely to suffer from LAEs. Recently, an exhaustive study (clinical, psychosocial, and biochemical evaluations) took place at Sainte-Justine University Health Center (Montreal, Canada), with the goal to characterize each of these morbidities in 250 survivors of childhood ALL (PETALE cohort). In addition, the genetic profile of each participant was obtained, and we used statistical and bioinformatics tools to perform association studies on this dataset in order to compare the frequency of genetic variants in survivors with or without LAEs. We evaluated cardiovascular and neurocognitive complications, as well as mood disorders such as anxiety and depression. Other risk factors, such as treatment and/or leukemia characteristics were also considered during the analysis to derive the best genetic predictors. Thus, using the candidate gene approach, we identified common variants in the MTR, PPARA, ABCC3, CALML5, CACNB2, and PCDHB10 genes that were associated with deficits in neurocognitive tests performance, whereas variants in the SLCO1B1 and EPHA5 genes were associated with anxiety and depression. Two variants, rs1805087 in the MTR gene and rs58225473 in the CACNB2 gene, are of particular interest since these associations were validated in an independent SJLIFE replication cohort (St. Jude Children's Research Hospital, Memphis, USA). The association analyses were complemented by an exome-wide association study, which identified several additional genes as potential modulators of the risk of developing treatment-related neurocognitive complications (genes AK8 and ZNF382), as well as anxiety and depression (genes PTPRZ1, MUC16, TNRC6C-AS1, APOL2, C6orf165, EXO5, CYP2W1, and PCMTD1). Variant rs61732180 in the ZNF382 gene was further validated in the replication SJLIFE cohort. To a great extent, we performed association analyses regarding treatment-related cardiac complications which identified several novel markers associated with these toxicities in the TTN, NOS1, ABCG2, CBR1, ABCC5, AKR1C3, NOD2, and ZNF267 genes in survivors of childhood ALL. In addition, we summarized the current knowledge on pharmacogenomic markers related to anthracycline-induced cardiotoxicity affecting pediatric cancer patients. We also included a brief overview of the applicability of reported findings to the PETALE cohort, validating several of them. Besides, we were interested in the complications that arise after a hematopoietic stem cell transplantation. We applied similar bioinformatics and statistical approaches to gain a more complete insight into the genetic component behind these life-threatening complications. Thus, an exome-wide association study was performed in a cohort of pediatric patients undergoing hematopoietic stem cell transplantation following a conditioning regimen containing busulfan. Our results identified new genetic variations conferring a higher risk of sinusoidal obstruction syndrome (notably in the UGT2B10, BHLHE22, and KIAA1715 genes) and acute graft-versus-host disease (ERC1, PLEK, NOP9, and SPRED1 genes), which could be useful for personalized prevention and treatment strategies. This work contributes to the understanding of the influence of genetic factors on the risk of developing treatment-related complications, both during treatment and in the long term. Furthermore, the reported genetic markers along with other known risk factors can lead to prediction models identifying patients at increased risk for these complications.