Mutations in the hereditary breast/ovarian cancer genes BRCA1/2 were shown to be synthetic lethal with poly(ADP-ribose) polymerase inhibitors (PARPi). This toxicity is assumed to derive from PARPi-induced DNA double strand breaks (DSBs) that necessitate BRCA function in homologous recombination (HR) and/or fork protection (FP). However, PARPi accelerates replication forks. While high-speed replication could cause DSBs, the finding that PARPi leads to single-stranded DNA (ssDNA) gaps/nicks suggests replication gaps could also or alone be the cause of synthetic lethality. Here, we demonstrate that PARPi toxicity derives from replication gaps. Isogenic cells deficient in BRCA1 or the BRCA1-associated FANCJ, with common DNA repair defects in HR and FP, exhibit opposite responses to PARPi. Deficiency in FANCJ, a helicase also mutated in hereditary breast/ovarian cancer and Fanconi anemia, causes aberrant accumulation of fork remodeling factor HLTF and limits unrestrained DNA synthesis with ssDNA gaps. Thus, we predict replication gaps as a distinguishing factor and further uncouple HR, FP and fork speed from PARPi response. BRCA-deficient cells display excessive gaps that are diminished upon resistance, restored upon re-sensitization and when targeted augment synthetic lethality with PARPi. Furthermore, we define the source of gaps to defects in Okazaki fragment processing (OFP). Unchallenged BRCA1-deficient cells have elevated poly(ADP-ribose) and chromatin-associated PARP1 but aberrantly low XRCC1 indicating a defective backup OFP pathway. Remarkably, 53BP1 loss resuscitates OFP by restoring XRCC1-LIG3 that suppresses the sensitivity of BRCA1-deficient cells to drugs targeting OFP or generating gaps. Collectively, our study highlights unprotected lagging strand gaps as a determinant of synthetic lethality, providing a new paradigm and biomarker for PARPi toxicity.

Le médulloblastome est une des tumeurs les plus fréquentes du système nerveux central chez l’enfant. Son impact clinique, ainsi que les effets secondaires engendrés par les traitements actuels, sont significatifs en matière de morbidité et de mortalité. La caractérisation moléculaire des tumeurs du système nerveux central a grandement évolué, et ce, particulièrement en ce qui concerne le médulloblastome. Des travaux antérieurs ont permis d’établir qu’un des sous-groupes de médulloblastome est caractérisé par l’activation de la voie sonic hedgehog. La mutation la plus fréquente menant à ce sous-type de médulloblastome est la mutation du gène suppresseur de tumeur PTCH1. Grâce au modèle de souris Ptch1+/-, des données issues de notre laboratoire ont permis de caractériser le développement de cette tumeur comme étant en deux étapes. Ce travail porte sur la caractérisation du mécanisme par lequel cette première étape, soit la perte d’hétérozygotie de Ptch1, survient. Tout d’abord, nous revisitons le rôle in vivo du corécepteur Boc dans la tumorigenèse. Selon nos résultats, la modulation de Boc ne semble pas avoir un impact significatif sur le développement tumoral dans des expériences de transplantation orthotopiques. Ensuite, nous démontrons que le ligand Shh augmente le dommage à l’ADN, ce qui mène à une hausse des évènements de recombinaisons qui peuvent causer une perte d’hétérozygotie. Nous tentons de moduler l’activité de Rad51 en observant une tendance non statistiquement significative des évènements de recombinaison avec des inhibiteurs de Rad51. Nous démontrons ensuite qu’un inhibiteur de Cdc7 permet la diminution des évènements de recombinaisons ainsi qu’une diminution du stress réplicatif de l’ADN. En intervenant sur le gène Mcm2 grâce à un modèle de souris transgénique, nous parvenons à prouver qu’une diminution de l’action de Mcm2 permet une diminution du stress réplicatif de l’ADN. En somme, la première étape du développement du médulloblastome sonic hedgehog-activé est la perte d’hétérozygotie de Ptch1. Celle-ci est caractérisée par une augmentation du dommage à l’ADN engendrant une hausse des évènements de recombinaison. Plusieurs cibles potentielles de modulation s’avèrent prometteuses pour un éventuel traitement ciblé. / Medulloblastoma is one of the most common central nervous system tumors of the child. Its clinical impact, as well as the adverse effects caused by current treatments, are significant in terms of morbidity and mortality. The molecular characterization of tumors of the central nervous system has greatly evolved, particularly in the case of medulloblastoma. Previous work has established that one of the medulloblastoma sub-groups is characterized by the activation of the sonic hedgehog (Shh) pathway. The most common mutation leading to this medulloblastoma subtype is the PTCH1 tumor suppressor gene mutation. Working with the Ptch1+/- mouse model, data from our la-boratory characterized the medulloblastoma tumorigenesis as a two-step process. This work focuses on the characterization of the mechanism by which this first step, the loss of heterozygosity of Ptch1, occurs. First, we revisit the in vivo role of the Boc coreceptor in the medulloblastoma tumor-igenesis. According to our results, Boc modulation does not seem to have a significant impact on tumor development. Next, we show that the Shh ligand increases DNA dam-age. This leads to an increase in recombination events which predispose to loss of het-erozygosity. We attempt to modulate Rad51 activity and observe a non-statistically sig-nificant trend to decrease recombination events with Rad51 inhibitors. We then demonstrate that Cdc7 inhibition reduces recombination events as well as DNA replica-tive stress. Using an Mcm2 transgenic mouse model, we demonstrate that a reduction in the action of Mcm2 reduces DNA replicative stress. To conclude, the first step in the development of Shh-activated medulloblastoma is the loss of heterozygosity of Ptch1. This is characterized by an increase in DNA damage leading to an increase in recombination events. Several potential modulation targets hold promise for possible targeted therapy.

Les sirtuines sont une famille conservée de déacétylases NAD+-dépendantes qui sont impliquées dans divers processus. Les humains possèdent 7 sirtuines (SIRT1-7) qui jouent un rôle dans plusieurs voies cellulaires, tandis que la levure Saccharomyces cerevisiae possède 5 membres (Sir2, Hst1-4) qui influencent plusieurs voies comme le cycle cellulaire ou le vieillissement. Une absence d’activité des sirtuines mène toutefois à des défauts de croissance, une thermosensibilité et l’apparition de dommages spontanés à l’ADN par des mécanismes mal élucidés. Pour mieux caractériser ce phénomène, ce mémoire met en lumière certains résultats venant d’un crible chimiogénétique réalisé par traitement au nicotinamide (NAM), un pan-inhibiteur des sirtuines. Nos résultats indiquent que le NAM entraîne chez la levure Saccharomyces cerevisiae une forte activation des voies de réponses aux dommages à l’ADN, et que les défauts de croissance sont principalement dus à l’hyperacétylation de la lysine 56 de l’histone H3 (H3K56), une modification post-traductionnelle qui est renversée par les sirtuines Hst3 et Hst4. Lors d’hyperacétylation de H3K56, la protéine Slx4 et le complexe PP4 sont requis pour la croissance de la levure en modulant les niveaux d’activation de la kinase Rad53 lors de la RDA. Également, certains résultats préliminaires inclus dans ce mémoire mettent en évidence un rôle de l’activité des sirtuines dans la régulation de la recombinaison homologue, l’une des voies de réparation de l’ADN. Ensemble, nos résultats suggèrent que la déacétylation des histones par les sirtuines permet de moduler la réponse aux dommages à l’ADN en présence de stress réplicatif. / Sirtuins are a conserved family of NAD+-dependent deacetylases that are involved in various processes. Humans have seven sirtuins (SIRT1-7) and play a role in several cellular pathways, while the budding yeast Saccharomyces cerevisiae has 5 members (Sir2, Hst1-4) and influence several pathways, such as the cell cycle or aging. Lack of sirtuin activity however leads to growth defects, thermosensitivity and spontaneous DNA damage by poorly understood mechanisms. To further characterize this phenomenon, this thesis highlights results obtained from a chemogenetic screen realized by treatment with nicotinamide (NAM), a pan-inhibitor of all sirtuins. Our results indicate that NAM causes strong activation of DNA damage-induced signaling in budding yeast Saccharomyces cerevisiae, and that growth defects are mainly due to histone H3 lysine 56 (H3K56) hyperacetylation, a post-translational modification reversed by sirtuins Hst3 and Hst4. During H3K56 hyperacetylation, the Slx4 protein and PP4 complex are both required for yeast growth by modulating the activation levels of Rad53 kinase during the DDR. Also, preliminary results included in this thesis highlight that proper regulation of homologous recombination, one of DNA repair pathways, is essential for growth in the presence of NAM-induced sirtuin inhibition. Together, our results suggest that chromosome-wide histone deacetylation by sirtuins can modulate DNA damage response in presence of replicative stress.

L'ADN de chaque cellule est constamment soumis à des stress pouvant compromettre son intégrité. Les bris double-brins sont probablement les dommages les plus nocifs pour la cellule et peuvent être des sources de réarrangements chromosomiques majeurs et mener au cancer s’ils sont mal réparés. La recombinaison homologue et la jonction d’extrémités non-homologues (JENH) sont deux voies fondamentalement différentes utilisées pour réparer ce type de dommage. Or, les mécanismes régulant le choix entre ces deux voies pour la réparation des bris double-brins demeurent nébuleux. Le complexe Mre11-Rad50-Xrs2 (MRX) est le premier acteur à être recruté à ce type de bris où il contribue à la réparation par recombinaison homologue ou JENH. À l’intersection de ces deux voies, il est donc idéalement placé pour orienter le choix de réparation. Ce mémoire met en lumière deux systèmes distincts de phosphorylation du complexe MRX régulant spécifiquement le JENH. L’un dépend de la progression du cycle cellulaire et inhibe le JENH, tandis que l’autre requiert la présence de dommages à l’ADN et est nécessaire au JENH. Ensembles, nos résultats suggèrent que le complexe MRX intègre différents phospho-stimuli pour réguler le choix de la voie de réparation. / The genome of every cell is constantly subjected to stresses that could compromise its integrity. DNA double-strand breaks (DSB) are amongst the most damaging events for a cell and can lead to gross chromosomal rearrangements, cell death and cancer if improperly repaired. Homologous recombination and non-homologous end joining (NHEJ) are the main repair pathways responsible for the repair of DSBs. However, the mechanistic basis of both pathways is fundamentally different and the regulation of the choice between both for the repair of DSBs remains largely misunderstood. The Mre11-Rad50-Xrs2 (MRX) complex acts as a DSB first responder and contributes to repair by both homologous recombination and NHEJ. Being at the crossroads of both DSB repair pathways, the MRX complex is therefore in a convenient position to influence the repair choice. This thesis unravels two distinct phosphorylation systems modifying the MRX complex and specifically regulating repair by NHEJ. The first relies on cell cycle progression and inhibits NHEJ, while the second requires the presence of DNA damage and is necessary for efficient NHEJ. Together, our results suggest a model in which the MRX complex would act as an integrator of phospho-stimuli in order to regulate the DSB repair pathway choice.

Les topoisomérases (topos) de type IA jouent un rôle primordial dans le maintien et l’organisation du génome. Cependant, les mécanismes par lesquels elles contrôlent cette stabilité génomique sont encore à approfondir. Chez E. coli, les deux principales topoisomérases de type IA sont la topo I (codée par le gène topA) et la topo III (codée par le gène topB). Il a déjà été montré que les cellules dépourvues des topos I et III formaient de très longs filaments dans lesquels les chromosomes ne sont pas bien séparés. Comme ces défauts de ségrégation des chromosomes sont corrigés par l’inactivation de la protéine RecA qui est responsable de la recombinaison homologue, il a été émis comme hypothèse que les topoisomérases de type IA avaient un rôle dans la résolution des intermédiaires de recombinaison afin de permettre la séparation des chromosomes. D’autre part, des études réalisées dans notre laboratoire démontrent que le rôle majeur de la topoisomérase I est d’empêcher la formation des R-loops durant la transcription, surtout au niveau des opérons rrn. Ces R-loops on été récemment identifiés comme des obstacles majeurs à l’avancement des fourches de réplication, ce qui peut provoquer une instabilité génomique. Nous avons des évidences génétiques montrant qu’il en serait de même chez nos mutants topA. Tout récemment, des études ont montré le rôle majeur de certaines hélicases dans le soutien aux fourches de réplication bloquées, mais aussi une aide afin de supprimer les R-loops. Chez E. coli, ces hélicases ont été identifiées et sont DinG, Rep et UvrD. Ces hélicases jouent un rôle dans la suppression de certains obstacles à la réplication. Le but de ce projet était de vérifier l’implication de ces hélicases chez le mutant topA en utilisant une approche génétique. Étonnamment, nos résultats montrent que la délétion de certains de ces gènes d’hélicases a pour effet de corriger plutôt que d’exacerber des phénotypes du mutants topA qui sont liés à la croissance et à la morphologie des nucléoides et des cellules. Ces résultats sont interprétés à la lumière de nouvelles fonctions attribuées aux topoisomérases de types IA dans la stabilité du génome. / Type 1A topoisomerases (topos) play a vital role in the maintenance and organization of the genome. However, the mechanisms by which they control genome stability still remain to be explored. In E. coli, the two type IA topoisomerases are topo I (encoded by topA) and topo III (encoded by topB). It has been shown that cells lacking topo I and III form very long filaments in which the chromosomes are not well separated. As the chromosome segregation defects are corrected by inactivation of the RecA protein, that is responsible for homologous recombination, it has been hypothesized that type IA topoisomerases have a role in the resolution of recombination intermediates to allow chromosome segregation. On the other hand, studies in our laboratory have shown that the major role of topoisomerase I is to prevent the formation of R-loops during transcription, especially at the rrn operons. These R-loops have been recently identified as major roadblocks to the progression of replication forks, which can cause genomic instability. We have genetic evidence suggesting similar effects may occur in our topA mutants. More recently, studies have shown the important role of certain helicases in eliminating roadblocks for replication forks that could sometimes be R-loops. In E. coli, these helicases have been identified and they are DinG, Rep and UvrD. The purpose of this project was to study the roles of these helicases in our topA mutant, using a genetic approach. Surprisingly, our results show that deletions of some of these genes have the effect of correcting rather than exacerbating topA mutant phenotypes that are related to the growth and cell and nucleoid morphology. These results are interpreted in the light of new functions assigned to the type IA topoisomerases in genome stability.

L’acétylation est une modification post-traductionnelle des protéines essentielles. Elle est impliquée dans bon nombre de processus cellulaires importants comme la régulation de la structure de la chromatine et le recrutement de protéines. Deux groupes d’enzymes, soient les lysines acétyltransférases et les lysines désacétylases, régulent cette modification, autant sur les histones que sur les autres protéines. Au cours des dernières années, de petites molécules inhibitrices des désacétylases ont été découvertes. Certaines d’entre elles semblent prometteuses contre diverses maladies telles le cancer. L’acide valproïque, un inhibiteur de deux des trois classes des désacétylases, a un effet antiprolifératif chez plusieurs organismes modèles. Toutefois, les mécanismes cellulaires sous-jacents à cet effet restent encore méconnus. Ce mémoire met en lumière l’effet pH dépendant de l’acide valproïque sur différentes voies cellulaires importantes chez la levure Saccharomyces cerevisiae. Il démontre que ce composé a la capacité d’inhiber la transition entre les phases G1 et S par son action sur l’expression des cyclines de la phase G1. De plus, il inhibe l’activation de la kinase principale de la voie activée suite à un stress à la paroi cellulaire. L’acide valproïque occasionne également un arrêt dans la réplication de l’ADN sans y causer de dommage. Il s’agit là d’un effet unique qui, à notre connaissance, n’est pas observable avec d’autres agents qui inhibent la progression en phase S. / Acetylation is an essential post-translational modification involved in many important cellular processes such as regulation of chromatin structure and proteins interactions. Two enzyme families, lysine acetyltransferases and lysine deacetylases, allow proper regulation of this modification both on histones and non-histones proteins. In recent years, the discovery of small deacetylase inhibitors has led to promising novel therapy in the treatment against various diseases such as cancer. Valproic acid, a class I and II deacetylase inhibitor, has been shown to have antiproliferative effects in various models. However, the cellular mechanisms underlying this effect remain unknown. This thesis highlights the pH-dependent effects of VPA on numerous important cellular pathways in the yeast Saccharomyces cerevisiae. Our results demonstrate that VPA inhibits the transition from G1 to S phase of the cell cycle by its action on the expression of G1 cyclins. Moreover, VPA inhibits the activation of the main kinase involved in the cell wall integrity pathway. Furthermore, VPA exposure also leads to DNA replication arrest in a DNA damage-independent manner. This is a unique effect that, to our knowledge, is not observable with other agents that inhibit S phase progression.

Recent knowledge suggests that the onset of cancer is modulated by the interplay of internal and external environmental factors along with numerous gene variants. Structural chromsomal aberrations in peripheral blood lymphocytes are considered as biomarkers of effect of genotoxic carcinogens and reflect elevated risk of cancer. Incomplete or deficient repair of double-strand breaks in DNA underlie chromosomal aberrations and the measurement of cytogenetic alterations may reflect interindividual differences in the response towards the mutagen. In this study the expected deficiences in the DNA repair capacity have been determined in incident oncological patients with breast, colorectal and urogenital cancers. The determination of chromosomal aberrations have been supplemented by the measurement of variants in genes involved in double-strand breaks repair (XRCC3, rs861539; RAD54L, rs1048771). Methodologically, we employed conventional cytogenetic analysis, cytogenetic analysis following the induction of chromocomal damage by bleomycin ("Challenge assay"), TaqMan discrimination analysis for the detection of allelic variants and statistical analyses. By using these methods we did not observe statistically signifiant differences either in chromosomal breaks (p=0,354) or in a percentage of cells with...

Introdução: No presente estudo foram avaliados biomarcadores na ocorrência de febre em pacientes neutropênicos após transplante de células tronco hematopoiéticas (TCTH). Objetivo: O objetivo principal foi avaliar os valores séricos de biomarcadores: proteína C reativa (PCR), procalcitonina (PCT) e IL-6 (interleucina-6) que possam identificar precocemente infecção em TCTH. Outro objetivo foi fatores de risco para óbito nessa população. Métodos: Os biomarcadores foram avaliados em um estudo prospectivo que incluiu 296 pacientes neutropênicos, submetidos a TCTH autólogo ou alogênico. Os biomarcadores PCT, PCR e IL-6 foram dosados nos seguintes momentos:dia da neutropenia constatada sem febre, evento febril ou hipotermia (T < 35ºC), 24 h após a febre ou hipotermia, 72 horas após a febre ou hipotermia e febre prolongada ou seja 48 horas após a coleta no momento anterior ou na persistência da febre, cinco dias após a coleta no momento anterior. Os dados clínicos e laboratoriais, foram avaliados até a evolução para alta ou o óbito, em uma planilha Excel® 2003 e foram processados pelos programas SPSS e STATA. Os pacientes foram classificados nos seguintes grupos (I- afebril; II- febre de origem indeterminada FOI e III- febre clinica ou microbiologicamente comprovada) em relação a cada marcador estudado (PCT, PCR e IL-6). Foram feitos cálculos para estabelecer área sob a curva ROC, sensibilidade, especificidade, para avaliação da febre e óbito. Para avaliar o desfecho óbito foi realizada análise multivariada com regressão logística stepwise. Resultados: Dos 296 pacientes, 190 apresentaram febre. Duzentos e dezesseis (73%) foram submetidos a transplantes autólogos e 80 (27,0%) alogênicos. Dos 80 casos de TCTH alogênicos 74 (92,6%) eram aparentados e apenas 6 (7,4%) aparentados. Dos 80 casos alogênicos 69 (86,3%) eram fullmatch e 11(13,7%) mismatch. Em relação aos grupos já citados acima, temos a seguinte distribuição: grupo I: 106 pacientes (35,8%); grupo II: 112 pacientes (37,8%) e grupo III: 78 (26,4%). Os valores de média e mediana da IL-6 no momento afebril no grupo I em relação ao grupo II (p = 0,013), apresentando valor significativamente maiores. Os níveis da PCR no grupo I diferiram de forma significativa dos encontrados no grupo III (p < 0,05). Os grupos diferiram em relação aos níveis de IL-6 e de PCR no momento febril. O grupo II apresentou concentrações de IL-6 e de PCR significativamente menores que o grupo III. Os melhores valores de corte de PCT para os momentos de coleta: febre, 24 horas após a febre, 72 horas de febre, e febre prolongada foram respectivamente: 0,32; 0,47; 0,46 e 0,35?g/L. No momento da febre a sensibilidade foi 52,3 e a especificidade 52,6 para o diagnóstico de infecção. Os melhores valores de corte de PCR para os momentos de febre, 24 horas após, 72 horas após e febre prolongada foram, respectivamente: 79, 120, 108 e 72 mg/L. No momento da febre a sensibilidade foi 55,4 e especificidade foi 55,1. Os melhores valores de corte de IL-6 para os momentos de febre, 24 h após, 72 horas após a febre e febre prolongada foram respectivamente: 34, 32, 16 e 9 pg/mL. A sensibilidade e especificidade no momento da febre foram respectivamente: 59,8 e 59,7. Na análise dos três biomarcadores no grupo de pacientes autólogos, verifica-se que só a IL-6 apresenta valores significativos nos momentos iniciais (afebril, febre e 24 horas após a febre). Os seguintes fatores de risco independentes foram identificados na análise multivariada: doador aparentado, doador não aparentado, infecção por Gram-negativo, DHL >= 390 (UI/L), ureia >= 25 (mg/dL) e PCR >= 120 (mg/L). Conclusões: IL-6 e PCR têm associação com diagnóstico precoce de infecção clinica ou microbiologicamente confirmada em neutropenia febril após TCTH. A associação dos três marcadores não apresentou nenhuma vantagem, e não melhorou a acurácia diagnóstica. A IL-6 foi o único biomarcador significativamente associado de forma precoce com infecção quando avaliado apenas pacientes submetidos a TCTH autólogos As variáveis independentes associadas com óbito foram: transplante alogênico, infecção por Gram-negativos, DHL >= 390UI/L no momento da febre e ureia >= 25 mg/dL no momento da febre e PCR >= 120 (mg/L) / Introduction: In the present study, biomarkers were assessed in the occurrence of fever in neutropenic patients upon hematopoietic stem cell transplantation (HSCT). Objective: The main objective was to assess the serum values of biomarkers: C-reactive protein (CRP), procalcitonin (PCT) and IL-6 (interleukin-6) which can early identify infection in HSCT. Another objective was risk factors for death in that population. Methods: The biomarkers were assessed in a prospective study which comprised 296 neutropenic patients submitted to autologous or allogeneic HSCT. The biomarkers PCT, CRP and IL-6 were dosed at the following moments: day of afebrile neutropenia, febrile event or hypothermia (T < 35ºC), 24 h upon fever or hypothermia, 72 hours upon fever or hypothermia and long-standing fever, that is, 48 hours upon the last sampling or at fever persistence, five days upon the last sampling. The clinical and laboratory data were assessed up to the evolution to discharge or death, in an Excel® 2003 spreadsheet and were processed by the SPSS and STATA software. Patients were classified in the following groups (I- afebrile; II- fever of unknown origin FUO and III- clinically or microbiologically proven fever) in regard to each biomarker studied (PCT, CRP and IL-6). Calculations were made to establish the area under the ROC curve, sensitivity, specificity, for the assessment of the evolution and death. In order to assess the death outcome, a multivariate analysis with stepwise logistic regression was conducted. Results: Out of the 296 patients, 190 had fever. Two hundred and sixteen (73%) were submitted to autologous transplantations and 80 (27.0%) to allogeneic ones. Out of the 80 cases of allogeneic HSCT, 74 (92.6%) were related and only 6 (7.4%) were unrelated. Out of the 80 allogeneic cases, 69 (86.3%) were fullmatch and 11(13.7%) were mismatch. In regard to the groups mentioned above, we have the following distribution: group I: 106 patients (35.8%); group II: 112 patients (37.8%) and group III: 78 patients (26.4%). The mean and median values of IL-6 at fever onset in group I in regard to group II (p = 0.013), presenting significantly higher values. The levels of CRP in group I differed significantly from those found in group III (p < 0.05). The groups differed in regard to the levels of IL-6 and CRP at fever onset. Group II presented IL-6 and CRP concentrations significantly lower than group III. The best cut-off values of PCT for sampling: fever onset, 24 hours upon fever, 72 hours of fever, and long-standing fever were, respectively: 0.32; 0.47; 0.46 and 0.35?g/L. At fever onset, sensitivity was 52.3 and specificity 52.6 for infection diagnosis. The best cut-off values of CRP for fever onset, 24 hours upon fever, 72 hours upon fever and long-standing fever were, respectively: 79, 120, 108 and 72 mg/L. At fever onset, sensitivity was 55.4 and specificity was 55.1. The best cut-off values of IL-6 for fever onset, 24 hours upon fever, 72 hours upon fever and long-standing fever were, respectively: 34, 32, 16 and 9 pg/mL. At fever onset, sensitivity and specificity were, respectively: 59.8 and 59.7. In the analysis of the three biomarkers in the group of autologous patients, it is observed that only IL-6 presents significant values at initial moments (afebrile, fever and 24 hours upon fever). The following independent risk factors were identified in the multivariate analysis: related donor, unrelated donor, Gram-negative infection, DHL >= 390 (UI/L), urea >= 25 (mg/dL) and CRP>=120 (mg/L). Conclusions: IL-6 and CRP are associated to the early diagnosis of clinically or microbiologically confirmed infection in post-HSCT febrile neutropenia. The association of the three biomarkers did not present any advantage, nor did it improve diagnostic accuracy. IL-6 was the only biomarker significantly associated at an early stage with infection when assessed only in patients submitted to autologous HSCT. The independent variables associated with death were: allogeneic transplantation, Gram-negative infection, DHL >= 390UI/L at fever onset and urea >= 25 mg/dL at fever onset and PCR >= 120 (mg/L)

O transplante de células-tronco hematopoiéticas tem sido a melhor opção terapêutica para muitas doenças. Seu sucesso, no entanto, depende de alguns fatores que influenciam a taxa de mortalidade. A doença do enxerto-contra-hospedeiro é uma causa de mortalidade. Apresenta duas formas, a aguda e a crônica, e ambas têm linfócitos T na patofisiologia. Outra causa são as infecções, cujos patógenos variam conforme o tempo de recuperação do sistema imune. O presente estudo avaliou a recuperação linfoide T com base no timo e distinção das subpopulações e citocinas nos pacientes que desenvolveram doença do enxerto-contra-hospedeiro crônica no primeiro ano de transplante. Os pacientes foram alocados no Hospital de Transplante Amaral Carvalho (Jaú/SP) e tinham entre 18 e 60 anos de idade. No pré-transplante, foram comparados com indivíduos saudáveis, pareados em idade. Após o transplante, todos os pacientes foram acompanhados por um ano e seis meses, para observação de possíveis eventos de doença do enxerto-contra-hospedeiro e/ou infecções. A análise laboratorial foi feita com o sangue do paciente, sendo a primeira antes do transplante, seguidas por mais quatro, com intervalos de três meses. Tais avaliações laboratoriais tinham por objetivos caracterizar a função tímica por quantificação de sjTREC; as subpopulações de linfócitos T, por citometria de fluxo e a análise de citocinas, por Luminex. Foram estudados 172 indivíduos, sendo 75 do transplante alogênico, 43 do transplante autólogo, além de 54 pessoas saudáveis. Nossos resultados mostraram que os pacientes apresentaram função tímica diminuída antes mesmo da realização do transplante. A função tímica enfraquecida foi um fator de risco para doença do enxerto-contrahospedeiro crônica e a recuperação do sistema imune foi melhor nos pacientes que não apresentaram doença do enxerto-contra-hospedeiro crônica após um ano do transplante. No entanto, a função tímica não foi diferente entre os pacientes que faleceram e os que estão vivos. No geral, não houve distinção quanto à apresentação das subpopulações de linfócitos T e à produção de citocinas entre os pacientes submetidos ao transplante alogênico que desenvolveram doença do enxerto-contra-hospedeiro crônica, relativamente aos demais pacientes. Com o tempo, foi observada a recuperação gradual do compartimento linfoide T e diminuição na incidência de infecções. A taxa de infecções não influenciou a apresentação das subpopulações de linfócitos T e a produção de citocinas nos pacientes que desenvolveram doença do enxerto-contrahospedeiro crônica em relação aos demais pacientes. Como conclusão, a função tímica apresentou-se deteriorada antes da realização do transplante, porém não foi determinante para que houvesse piora na evolução clínica após o transplante. Os pacientes que desenvolveram doença do enxerto-contra-hospedeiro crônica, independentemente da incidência de infecções, apresentaram semelhança no perfil das subpopulações de linfócitos T e das citocinas, quando comparados aos demais / Hematopoietic stem cell transplantation has been the best therapeutic option for many diseases. Its success depends on some factors that influence the mortality rate. Graftversus- host disease is one cause of mortality. It has two forms, acute and chronic, and both have T lymphocytes in their pathophysiology. Other causes are infections, whose pathogens vary according to immune system recovery time. The present study evaluated the lymphoid T recuperation through the thymus and the differentiation of subpopulations and cytokines in patients who developed chronic graft-versus-host disease at the first year of transplantation. The patients were allocated at Hospital de Transplantes Amaral Carvalho (Jaú/SP). They were between 18 and 60 years old. At pre-transplant phase, patients were compared to healthy individuals, age-matched. After transplantation, they were all assisted for one year and six months, so that graft-versushost disease\'s and infections\' events could be observed. The laboratory analysis was done by blood sample; the first occurred before the transplant, followed by four more, every three months. Laboratory examinations were performed to characterize thymic function by quantification of sjTREC; T lymphocyte subpopulations, by flow cytometry, and cytokine analysis, by Luminex. A total of 172 individuals were studied: 75 allogeneic transplant patients, 43 autologous transplant patients and 54 healthy persons. Our results showed that patients presented thymic function impaired even before the transplant. The weakening of the thymic function was a risk factor for chronic graft-versus-host disease and immune system recovery was better in patients who did not develop chronic graft-versus-host disease after one year of transplantation. However, the thymic function was not different between patients who died and those who remained alive. In general, there was no distinction of the presentation of T lymphocyte subpopulations and cytokines production among patients who underwent allogeneic transplant and developed chronic graft-versus-host disease, in comparison to the other patients. Over time, a gradual recovery of the T lymphoid compartment and a decrease in the infections incidence were observed. The infection rate did not influence the presentation of the T lymphocyte subpopulations and the production of cytokines in patients who developed chronic graft-versus-host disease in comparison to the other patients. In conclusion, the thymic function was impaired before transplantation, but it was not relevant for clinical evolution worsening after transplantation. Patients who developed chronic graft-versus-host disease, regardless of the incidence of infections, showed similar profile of T lymphocytes subpopulations and cytokines, relatively to other patients

O transplante de células tronco hematopoéticas alogênico e autogênico na leucemia mielóide aguda em primeira remissão completa: analise de 62 pacientes. Os pacientes foram submetidos a transplante de células tronco hematopoéticas alogênico e autogênico. Ao final do estudo estavam vivos no alogênico 43,3% e no autogênico 62,5%. Consolidação intensiva teve melhor sobrevida no alogênico. Os pacientes com DECH aguda grau II tiveram melhor sobrevida. Dois pacientes com DECH crônica extensa morreram. Óbito por infecção ocorreu com maior freqüência no alogênico seguido de recidiva. No autogênico a recidiva foi a principal causa de óbito. Morte por toxicidade ocorreu em 47% dos pacientes que foram a óbito no alogênico e em 8,3% no autogênico. Na analise múltipla de Cox a consolidação intensiva e DECH crônica, tiveram significância. / The allogeneic and autologous hematopoietic stem cell transplantation in acute myeloid leukemia in first complete remission: analyses of 62 patients. The patients were submitted to allogeneic and autologous hematopoietic stem cell transplantation. The end of the study were kept alive in allogeneic 43,3% and in autologous 65,2%. Patient in allogeneic who were consolidated had better survival. Patients with acute GVHD grade II had better survival. Two patients with chronic GVHD in intense, died. Infection was the most frequent dead cause in allogeneic following relapse. In autologous the relapse was the principal cause of death. Toxicity occurred in 47% of patients who died in allogeneic and 8,3% in autologous. In cox multiple analyses intensive consolidation and chronic GVHD had significance.