Il y a environ 13 000 Inuit qui vivent dans les quatorze communautés côtières du Nunavik, consommant des aliments locaux issus de la chasse, la pêche, la trappe et la cueillette. Malgré les bienfaits documentés liés à la consommation d'aliments locaux et à leur mode de vie traditionnel, sur leur santé et leur bien-être, certaines particularités culturelles (e.g. consommation de viande crue et d'eau naturelle, surpeuplement des logements) peuvent faire augmenter les risques d'exposition à certaines maladies infectieuses. L'enquête de santé Qanuirlipitaa? 2017 (Q2017) a été mise sur pied afin d'établir un portrait de la santé des habitants du Nunavik. Le volet portant sur les maladies zoonotiques et gastro-entériques visait, entre autres, à améliorer les connaissances en lien avec l'épidémiologie du parasite Toxoplasma gondii et de la bactérie Helicobacter pylori. Au total, 1326 Nunavimmiuts ont participés à Q2017 dont 303 avaient également participé à l'enquête de santé Qanuippitaa? 2004. Les autorités en santé publique s'intéressent à Toxoplasma gondii car il est un parasite excrété par les félins et qui cause des problèmes principalement chez les femmes enceintes qui n'y ont jamais été exposées et les individus immunosupprimés. Au Nunavik, une séroprévalence élevée d'anticorps contre T. gondii a été observée durant l'enquête de 2004 (~60%) et l'on soupçonne que la consommation d'aliments locaux et/ou d'eau naturelle contaminés par le parasite soient les principales sources d'exposition. En vue d'élaborer les questions de Q2017, une méta-analyse portant sur l'association entre la présence d'anticorps contre T. gondii et la consommation de viande crue ou peu cuite, toutes espèces animales confondues, a été effectuée. En utilisant un modèle à effet aléatoire, des mesures d'association ont été estimées selon différents devis d'étude (cohorte, cas-témoins et transversales) tout en tenant compte de l'hétérogénéité et de la qualité des études. Nos résultats appuient que les personnes mangeant de la viande crue ou peu cuite présentent un risque (rapport de prévalence ou d'incidence variant de 1,2 à 1,3) et une chance (rapports de cote variant de 1,7 à 3,0) plus élevés d'avoir des anticorps contre T. gondii, par rapport à celles qui cuisent la viande. Lors de Q2017, 43% des Nunavimmiuts possédaient des anticorps contre T. gondii. Grâce à trois différents modèles de régression de type Poisson robuste employant différentes variables, nous avons observé que la séroprévalence était corrélée avec la consommation de mollusque (rapports de prévalence [RP] variant de 1,02 à 1,21) dans un modèle et chaque augmentation de deux consommations de béluga (RP variant de 1,01 à 1,03), de foie de phoque (RP variant de 1,01 à 1,02) et d'oies (RP variant de 1,01 à 1,02), dans les deux autres modèles. La consommation d'eau provenant d'une source naturelle (RP de 1,47) ou municipale (RP de 1,42) étaient aussi positivement corrélée à une séroprévalence plus élevée comparativement à la consommation d'eau embouteillée dans un modèle, quoique les résultats étaient aussi compatibles avec la valeur nulle. Les autorités en santé publique du Nunavik s'intéressent aussi à Helicobacter pylori, une bactérie qui prolifère dans l'estomac humain, provoquant une inflammation chronique (gastrite) menant jusqu'à des ulcères gastro-duodénaux et le cancer. La bactérie a été détecté chez 71% des participants qui ont fourni des selles tandis que les anticorps ont été détectés chez 73% et 77% de ceux qui ont fourni du sérum, en 2017 et en 2004, respectivement. La colonisation par H. pylori au Nunavik est considérée élevée par rapport au reste de la province, mais est similaire aux autres communautés autochtones nord-américaines. Un diagnostic antérieur d'infection à H. pylori, de gastrite ou d'ulcères gastro-duodénaux a été observé, respectivement, dans 28,4%, 11,2% et 2,4% des dossiers médicaux. La présence d'H. pylori était associée positivement au fait d'habiter la Côte d'Hudson (PR de 1,11), à l'âge (relation curvilinéaire), au nombre de personnes dans le ménage (PR de 1,03) et négativement à la consommation d'eau embouteillée (PR variant de 0,72 à 0,86) tandis que la consommation d'alcool était légèrement associée à une réduction de la prévalence (PR de 0,96). La sensibilité et la spécificité de la sérologie, comparativement à la détection des antigènes dans les selles, sont de 0,85 et 0,67.

During acute and chronic infectious diseases hosts develop complex immune responses to cope with bacterial persistence. Depending on a variety of host and microbe factors, outcomes range from peaceful co-existence to detrimental disease. Mechanisms underlying immunity to bacterial stimuli span several spatiotemporal magnitudes and the summation of these hierarchical interactions plays a decisive role in pathogenic versus tolerogenic fate for the host. This dissertation integrates diverse data from immunoinformatics analyses, experimental validation and mathematical modeling to investigate a series of hypotheses driven by computational modeling to study mucosal immunity. Two contrasting microbes, enteroaggregative Escherichia coli and Helicobacter pylori, are used to perturb gut immunity in order to discover host-centric targets for modulating the host immune system. These findings have the potential to be broadly applicable to other infectious and immune-mediated diseases and could assist in the development of antibiotic-free and host-targeted treatments that modulate tolerance to prevent disease. / Ph. D.

Les systèmes toxine-antitoxine (TA) sont de petits modules génétiques largement présents dans les génomes bactériens. Ils codent pour une petite protéine toxique et une antitoxine. Ils sont classés en six types en fonction de la nature et du mode d'action de l'antitoxine. Ce travail a porté sur l'étude du type I, pour lequel l'antitoxine est un ARN antisens qui cible l'ARNm de la toxine afin de réprimer son expression. Au cours de cette thèse, nous avons étudié le système aapA3/IsoA3, codé sur le chromosome du pathogène gastrique humain Helicobacter pylori. À ce jour, la plupart des systèmes TA ont été étudiés à l'aide de systèmes d'expression artificiels, qui ne permettent pas de caractériser la régulation transcriptionnelle ou post-transcriptionnelle. En utilisant la létalité induite par l’expression chromosomique de la toxine obtenue en absence d’antitoxine, nous avons développé une sélection génétique de mutants suppresseurs révélés par séquençage haut-débit. Cette approche, appelée FASTBAC-Seq, nous a permis de cartographier une myriade de déterminants de toxicité localisés dans les régions codantes et non codantes du gène de la toxine AapA3. En particulier, certaines de ces mutations ont révélé l'existence de tige-boucles ARN transitoires qui agissent de manière co-transcriptionnelle pour empêcher l'initiation de la traduction pendant la synthèse de l'ARNm codant pour la toxine. Ces structures ARN métastables fonctionnelles sont nécessaires pour découpler les processus de transcription et de traduction et permettent la présence de ces gènes toxiques sur le chromosome bactérien. Bien que les ARNm non traduits deviennent rapidement instables, nos travaux ont également révélé l'existence de deux tige-boucles protectrices situées aux deux extrémités de l'ARNm. Ces structures secondaires empêchent des activités exonucléolytiques agissant en 5' et 3'. Dans l’ensemble, notre travail met en évidence les conséquences de la forte pression de sélection pour limiter l'expression des toxines sous laquelle évoluent les systèmes TA. Cela nous a permis de mieux comprendre l’influence du repliement secondaire des ARNm, non seulement lors de la régulation posttranscriptionnelle, mais aussi co-transcriptionnelle de l’expression de cette famille particulière de gènes. Ces caractéristiques de régulation basées sur l'ARN peuvent être exploitées à l'avenir pour des applications biotechnologiques (p. ex., production accrue de protéines par stabilisation d'ARNm) ou biomédicales (p.ex., développement de stratégies antimicrobiennes alternatives pour l'activation de la synthèse de toxines). / Toxin-antitoxin (TA) systems are small genetic modules widely present in bacterial genomes. They usually code for a small toxic protein and its cognate antitoxin and can be classified into six types depending on the nature and mode of action of the antitoxin. This work focuses on the study of type I, for which the antitoxin is an antisense RNA that targets the toxin mRNA to inhibit its expression. We characterized the aapA3/IsoA3 system, encoded on the chromosome of the human gastric pathogen Helicobacter pylori. To date, most TAs have been studied using artificial expression systems, which do not allow the characterization of transcriptional or post-transcriptional regulation. Taking advantage of the lethality induced by the toxin chromosomal expression in the absence of antitoxin, we developed a high-throughput genetic selection of suppressor mutations revealed by Next-Generation Sequencing. This approach, named FASTBAC-Seq, allowed us to map a myriad of toxicity determinants located in both, coding and noncoding regions, of the aapA3 toxic gene. More precisely, some suppressor mutations revealed the existence of transient RNA hairpins that act co-transcriptionally to prevent translation initiation while the toxinencoding mRNA is being made. Such functional RNA metastable structures are essential to uncouple the transcription and translation processes and allow the presence of these toxic genes on bacterial chromosomes. Although untranslated mRNAs become rapidly unstable, our work also revealed the presence of two protective stem-loops located at both mRNA ends that prevent from both, 5’ and 3’ exonucleolytic activity. Altogether, our work evidenced the consequences of the strong selection pressure to silence toxin expression under which the TAs evolve, and highlighted the key role of mRNA folding in the co- and post-transcriptional regulation of this family of genes. These RNA-based regulatory mechanisms may be exploited in the future for biotechnological (e.g., increased protein production through mRNA stabilization) or biomedical (e.g., development of alternative antimicrobial strategies aiming at the activation of toxin synthesis) applications.

Das humane Magenpathogen Helicobacter pylori (H. pylori) besiedelt den menschlichen Magen und kann zu der Entstehung schwerwiegender Krankheiten wie Magenkrebs und Magengeschwüren führen. Die Pathogenese ist eng mit dem bakteriellen Typ IV Sekretionssystems (T4SS) assoziiert, das die Translokation des Effektorproteins CagA in die Wirtszelle vermittelt. Bisher ist noch unbekannt, in welchem Ausmaß wirtszellspezifische Faktoren die T4SS induzierte Pathogenese beeinflussen. Dieser Aspekt wurde in dieser Arbeit durch die Analyse verschiedenster Zelllinien das erste Mal systematisch untersucht. Interessanterweise unterschied sich die zelluläre Antwort auf die T4SS spezifische Infektion erheblich in Abhängigkeit der verwendeten Zelllinie. Die Ergebnisse beweisen, dass Wirtszellfaktoren eine ebenso große Rolle in der H. pylori induzierten Pathogenese spielen wie bakterielle Effektoren. Zusätzlich wurde in dieser Arbeit eine genomweite Screening-Methode etabliert, die es ermöglicht, neue Komponenten des T4SSs, translozierte NF-B Effektoren und bakterielle Adhäsine zu identifizieren. Auch der Einfluss von CagA auf den EGF-Rezeptor wurde hier näher untersucht. Der Rezeptor steht ebenfalls eng mit der Entstehung von Krebs in Verbindung. Hierbei stellte sich heraus, dass CagA die Endozytose des EGF-Rezeptors durch die Aktivierung der Nicht-Rezeptor Tyrosinkinase c-Abl hemmt und dadurch die Rezeptorpopulation auf der Wirtszelloberfläche erhöht. Interessanterweise führt dieser Effekt jedoch nicht zu einer Verstärkung der EGF-Rezeptor Signaltransduktion. Vielmehr kommt es zu einer Hemmung der EGF-Rezeptor Transaktivierung und zu einer Blockade der EGF vermittelten Wundheilung. Die Daten weisen auf eine Rolle des EGF-Rezeptors in der H. pylori induzierten Geschwürbildung hin. Auch der zu Grunde liegende molekulare Mechanismus der Rezeptor-Inhibierung konnte hier entschlüsselt werden, der sowohl von CagA als auch von der Phosphatase SHP-2 gesteuert wird. / The human gastric pathogen Helicobacter pylori (H. pylori) elicits a tremendous medical burden because of its causative association with peptic ulcer disease and gastric cancer. The pathogenic potential of H. pylori is intricately linked to the expression of a pathogenicity island encoded type IV secretion system (T4SS), which translocates the bacterial effector protein CagA into the eukaryotic host cell. The role of host cell determinants in T4SS mediated pathogenesis has not yet been systematically examined. To elucidate the role of host cell factors within T4SS induced host cell responses, different eukaryotic cell lines were analyzed systematically for respective phenotypes. Remarkably, T4SS mediated host responses among these cell lines varied considerably, thereby demonstrating the importance of host cell components in H. pylori induced pathogenesis. In addition, a H. pylori genome wide bacterial screen for factors important in pathogenesis, such as unknown T4SS components or novel NF-kappaB effector molecules, was developed and optimized. The precise function of the prominent effector protein CagA remains unclear. To functionally characterize the role of CagA, its impact on the epidermal growth factor (EGF)-receptor pathway was analyzed. The results suggest a mechanism where EGF-receptor endocytosis is completely blocked by a CagA induced activation of c-Abl, leading to an elevated receptor surface exposition. Surprisingly, EGF-receptor transactivation and EGF-dependent wound healing are selectively blocked during prolonged infections as well, indicating that an increased receptor-population on the cell surface does not necessarily promote signaling. This data suggests a role for the EGF-receptor in H. pylori- induced ulcer disease. The underlying molecular mechanism was identified as being SHP-2 and CagA dependent.

Die transkriptionelle Aktivierung des HDC Gens sowie des Chromogranin A Gens in ECL-Zellen der Magenmucosa repräsentiert einen zentralen Mechanismus der Säureregulation durch Gastrin und scheint ausserdem Bedeutung für die Pathogenese der gastroduodenalen Ulkuskrankheit zu haben. Unsere Untersuchungen identifizieren erstmals die molekularen Mechanismen der Gastrin-abhängigen Regulation beider Gene und definieren die beteiligten Transkriptionsfaktoren, regulatorischen DNA-Elemente und intrazellulären Signalwege. Des weiteren wurde durch transgene Untersuchungen die transkriptionelle Regulation des ChromograninA Gens in vivo bestätigt und die neuroendokrin-spezifische Expression eines 4.8kB-langen CgA-Promotorfragmentes demonstriert. Als pathobiologisch relevante Aktivatoren des HDC Gens konnten oxidativer Stress sowie die H. pylori Infektion identifiziert und hinsichtlich ihrer molekularen Wirkungen auf das Schlüsselgen der Histaminsynthese im Magen charakterisiert werden. Diese Ergebnisse dokumentieren einen potentiellen Mechanismus für die Interaktion beider Stimuli mit den physiologischen Regelkreisen der Magensäureregulation und können durch die Definition neuer molekularer Angriffspunkte möglicherweise zur Entwicklung innovativer Therapieansätze beitragen. / Transcriptional activation of the genes encoding histidine decarboxylase and chromogranin A represents a key mechanism of gastrin-dependent acid regulation and also appears to be involved in the pathogenesis of gastroduodenal ulcer disease. Our results for the first time identify the molecular mechanisms underlying gastrin-dependent activation of both genes, and define the transcription factors, regulatory DNA elements and signal transduction pathways involved in this process. Furthermore, transgenic studies confirmed the principle of gastrin-dependent transcriptional activation of the chromogranin A gene in vivo, and demonstrated neuroendocrine-specific expression of a 4.8kB-CgA promotor fragment. In addition, the pathobiological stimuli oxidative stress and H. pylori were molecularly characterized regarding their activating effects on the key gene of gastric histamine sythesis. These results provide potential mechanisms for the interaction of both stimuli with regulatory circuits of gastric acid secretion, and can probably contribute via definition of new molecular targets to the development of inovative therapeutic strategies.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O carcinoma gÃstrico à a segunda causa de morte por cÃncer no mundo. No Cearà à o segundo mais freqÃente entre os homens e o terceiro entre as mulheres. Dos cÃnceres gÃstricos os adenocarcinomas representam em torno de 95%. A doenÃa tem sido associada a fatores genÃticos e ambientais sendo demonstrada Ãntima relaÃÃo com a infecÃÃo por Helicobacter pylori, principalmente associada à presenÃa do gene cagA e genÃtipos vacAs1m1. Entretanto, apesar dos mecanismos pelos quais a bactÃria promove a carcinogÃnese gÃstrica ainda nÃo estarem esclarecidos, uma das hipÃteses seria atravÃs da inativaÃÃo de supressores tumorais. O objetivo do presente trabalho foi verificar, em adenocarcinomas gÃstricos, se a presenÃa de H. pylori, e de seus genes cagA e vacA, està relacionada com a mutaÃÃo e/ou alteraÃÃo na expressÃo protÃica dos supressores tumorais p53 e p27. Neste estudo, 74 amostras de pacientes foram analisadas quanto à presenÃa de H. pylori, cagA+ e os genÃtipos de vacA, pela reaÃÃo em cadeia da polimerase (PCR). A anÃlise mutacional do gene p53 foi realizada por PCR-SSCP e a detecÃÃo da mutaÃÃo/superexpressÃo do p53 e expressÃo da proteÃna p27 pelo mÃtodo imunohistoquÃmico. A bactÃria foi detectada em 95% das amostras, das quais 63% eram cagA(+). Dentre os alelos de vacA, observou-se predomÃnio de s1 (74%) e m1 (82%), associados em 69% dos casos. Na anÃlise mutacional do p53 verificou-se que 72% dos casos exibiram alteraÃÃo no padrÃo de mobilidade eletroforÃtica, sendo esta associada significativamente à presenÃa do gene cagA. Por outro lado, apenas 29% dos casos apresentaram detecÃÃo pelo mÃtodo imunohistoquÃmico, nÃo sendo encontrada associaÃÃo com a H. pylori. A proteÃna p27 demonstrou acentuada reduÃÃo em sua expressÃo (detectada em apenas 19% dos casos), nÃo demonstrando atividade compensatÃria em relaÃÃo à proteÃna p53 mutada e sem associaÃÃo estatÃstica dos casos negativos com a presenÃa da H. pylori. Finalmente, os resultados sugerem que estes supressores simultaneamente inativados podem ser o ponto chave da desregulaÃÃo do ciclo celular que, associados a outros fatores, favoreÃam o desenvolvimento e progressÃo dos adenocarcinomas gÃstricos. Hà indÃcios de que a presenÃa bacteriana, e dos seus genes cagA(+) e vacA/s1m1, possam influenciar, de forma nÃo esclarecida, as alteraÃÃes moleculares ocorridas nos supressores tumorais p53 e p27. / Gastric carcinoma is the second cause of death by cancer in the world. On State of Ceara-Brazil is the second most frequent type of cancer in men and third in women. Adenocarcinomas account for approximately 95% of all malignant gastric neoplasms. It has been associated to genetic and environmental factors and a intimate relationship between the infection by the bacteria Helicobacter pylori and the gastric carcinoma have been related. The presence of the cagA gene and specific genotypes (s1m1) of the gene vacA have been detected in more pathogenic strains. Although the precise molecular mechanisms by which H. pylori could promote the process of gastric carcinogenesis are under investigation, one hypothesized mechanism involves the tumor supressor genes inactivation. The aim of the present study was to verify if the presence of Helicobacter pylori, cagA and vacA genes is related to mutations in the tumor supressor gene p53 and altered expression of p53 and p27 proteins in gastric adenocarcinomas. Seventy-four (74) samples were analyzed to detect the presence of H. pylori, cagA and genotypes of vacA by Polymerization Chain Reaction (PCR). The mutational analysis of p53 gene was performed by PCR-SSCP (Polymerization Chain Reaction for analysis of the Single-strand Conformation Polymorphism). Analysis of mutation or overexpression of p53 protein and p27 expression was detected by the immunohistochemical method. The bacteria was detected in 95% of the samples, 63% was cagA(+). Among the vacA allele it was observed prevalence of s1 (74%) and m1 (82%), associated in 69% of the cases. Mutation analysis of p53 demonstrated 72% of the cases with altered electrophoretic mobility; The alterations were significatively more frequent in the presence of the cagA gene. Immunohistochemical analysis detected only 29% of cases with the expression of p53 protein. The protein p27 showed accentuated reduction in its expression (detected in only 19% of the cases), it has not demonstrated compensatory activity in relation to the p53 altered protein, neither association to H. pylori presence. Finally, these data suggest that simultaneous inactivation of these tumor suppressors genes may be the key point of deregulation of the cellular cycle that, associated to the other factors, favor the development and progression of the gastric cancer. There is some evidence that the bacterial presence, cagA and vacA/s1m1 genes, may influence, in a not understood way, the alterations observed in the tumor suppressors p53 and p27.

Atualmente, muitas são as diretrizes na literatura quanto à influência do Helicobacter pylori na Doença do Refluxo Gastroesofágico. Alguns autores acreditam que o H. pylori poderia ter um efeito protetor para o desenvolvimento na DRGE e outros até mesmo concluem que o agente possa ser um fator agravante na doença. Muitas publicações nos alertam para o desenvolvimento de sintomas da DRGE, ou mesmo da esofagite, em uma porcentagem razoável de pacientes erradicados pelo esquema tríplice para tratar o H. pylori, sendo que aproximadamente 10% teriam DRGE. Na verdade, por essas dúvidas, ainda não foi estabelecido um consenso quanto à importância do H. pylori na etiopatogenia da DRGE e suas complicações. Fato também discutido, seria a importância das cepas para a formação da esofagite em pacientes submetidos à erradicação. Talvez as mais virulentas, assim como a presença da “ilha de patogenicidade"(cagA) ou algumas cepas vacuolizantes (vacA), teriam uma maior relação com a prevenção da esofagite. Outro mecanismo importante, apontado por muitos, para a formação da esofagite em pacientes erradicados seria a elevação do índice de Massa Corpórea nesse grupo de pacientes erradicados associados ou não à presença da hérnia hiatal e justificados pela melhor qualidade de vida após melhora dos sintomas depois da erradicação. Em nosso estudo, 148 pacientes com úlcera péptica ativa ou cicatrizada receberam esquema tríplice de erradicação para o Helicobacter pylori e foram submetidos a exame endoscópico e ao teste histopatológico das amostras colhidas por biópsias de corpo e antro, teste respiratório com Carbono 14 e urease, antes e após o tratamento. Realizamos a genotipagem do agente, através do PCR, separando amostras de corpo e de antro, para determinar as cepas do agente. Os pacientes foram seguidos ambulatorialmente por um ano e avaliados quanto à melhora ou piora dos sintomas relacionados a DRGE (pirose) e sintomas considerados inespecíficos como a dor epigástrica; também procuramos quantificar o ganho ou perda do IMC. Encontramos 28 pacientes (18,9%) com esofagite erosiva (24 grau A e 4 grau B de Los Angeles) endoscópica após o tratamento do agente. Deste grupo, somente 3 pacientes que não tinham sintomas desenvolveram pirose (2%). A grande maioria dos pacientes se beneficiou com o tratamento, mostrando que 69 46,6%) melhoraram da pirose e outra grande maioria melhorou dos sintomas inespecíficos. Em 18 pacientes ulcerosos com esofagite, a análise de fragmentos de corpo foi cagA positiva (64,3%) e em amostras de antro 21 eram cagA positivos (75%). Assim como no grupo geral, as cepas vacuolizantes s1b/m1 e s1b foram, respectivamente, as mais encontradas no grupo da esofagite endoscópica. Houve ligeiro aumento nos Índices de Massa Corpórea em pacientes com e sem esofagite, sendo estatisticamente mais significativo nos 120 pacientes sem esofagite. Apesar do aparecimento da esofagite erosiva endoscópica em número razoável de pacientes, a sintomatologia não foi fator determinante, pois muitos melhoraram dos sintomas após o tratamento, e a erradicação não foi importante para determinar o grau de esofagite erosiva. Não foi encontrada nenhuma relação entre a genotipagem do agente e o desenvolvimento de esofagite endoscópica. O aumento de IMC, também não justifica, em nosso estudo a esofagite em pacientes ulcerosos tratados contra o H. pylori. / Nowadays, there are many directrixes in literature as to the influence of Helicobacter pylori, in the Disease of Gastroesophagic reflux. Some authors believe that H. pylori could have a protective effect to the development of GERD, and others even conclude that the agent may be an aggravating factor in the disease. Many publications allert us to the development of symptoms of GERD, or even the esophagitis,in a reasonable percentage of erradicated patients by the triplicit scheme to treat H. pylori, and 10%, approximately, would have GERD. In fact, due to these doubts, a consensus has not been established yet to the importance of H. pylori in the GERD’s etiopathogenic and its complications. The strains importance to the formation of esophagitis in patients submitted to erradication is another fact that has also been discussed. Maybe the most virulent ones, as the presence of “pathogenical island"(cagA) or some other vacuolating cytotoxin (vacA), would have a larger relation in the esophagitis prevention. Another important mechanism, pointed by many, to the formation of esophagitis in erradicated patients would be the elevation of Body Mass Index in this group of eradicated patients associated or not to the presence of hiatal hernia and justified by a better quality of life due to symptoms’ improvement after erradication. In our studies, 148 patients with active or healed peptic ulcer received triplicit scheme of erradication to the Helicobacter pylori and were submitted to endoscopic exams and histopathologic test of gathered samples by body and antro biopsies, respiratory test with carbon 14 and ureasis, before and after treatment. We have done the agent genotyping, through the PCR, separating samples of body and antro, to determine the agent Cepas. The patients have been followed ambulatorially for a year and evaluated as to the improvement or worsening of the symptoms related to GERD (pyrosis) and symptoms considered non-specific as epigastric pain; we have also tried to quantify the gain or loss of Body Mass Index. We found 28 patients(18.9%) with endoscopic erosive esophagitis (24 degree A and 4 degree B of Los Angeles) after agent’s treatment. In this group, only three patients who had no symptoms developed pyrosis (2%). Most of the patients benefitted from treatment showing that 69 (46.6%) presented improvement in pyrosis and another great majority improved non-specific symptoms. In 18 ulcered patients with esophagitis, the body analysis fragments was positive cagA (64.3%)and in antro samples of 21 were positive cagA (75%). As in the general group, the vacuolizing cepas slb/ml and slb were, respectivelly, the most found in the endoscopic esophagitis group. There was a slight raise in the BMI in patients with and without esophagitis, and it is, statistically more meaningful in the 120 patients without esophagitis. Even though there was the appearance of endoscopic erosive esophagitis in a reasonable number of patients, the symptmology was not a determining factor, because many have got better after the treatment, and erradication was not important to determine the erosive esophagitis. It was not found any relation between the agent genotyping and the development of endoscopic esophagitis. The raise of BMI does not justify in our study the esophagitis in ulcered patients treated against H. pylori.

Die kontinuierliche Rezirkulation von Immunzellen durch periphere und sekundäre lymphatische Organe (SLOs) ist Bestandteil der Immunüberwachung und wichtig für die Aufrechterhaltung und Funktionsbereitschaft des Immunsystems. Der homöostatische Chemokinrezeptor CCR7 vermittelt dabei nicht nur die Rezirkulation von Lymphozyten durch SLOs, sondern scheint auch an der homöostatischen Rezirkulation von Lymphozyten durch nicht-lymphoide periphere Gewebe beteiligt zu sein. Im Rahmen dieser Arbeit wurde mithilfe von CCR7-defizienten Mäusen die funktionale Bedeutung von CCR7 für die homöostatische Rezirkulation von Lymphozyten durch das Peritoneum untersucht und nachgewiesen, dass CCR7 der dominante Chemokinrezeptor ist, der unter physiologischen Bedingungen die Transitzeit von Lymphozyten durch das Peritoneum festlegt. Die gestörte Rezirkulation von Lymphozyten begünstigte außerdem die Entstehung von tertiären lymphoiden Organen (TLOs) in der Magenschleimhaut von CCR7-defizienten Mäusen. Untersuchungen zur zellulären und molekularen Grundlage dieser und weiterer pathomorphologischer Veränderungen in der Magenschleimhaut von CCR7-defizienten Mäusen verdeutlichten die Funktion von CCR7 für die Etablierung von zentraler und peripherer Toleranz gegenüber gastrischen Antigenen. Fehlt CCR7, dann entwickelten Mäuse eine spontane Autoimmungastritis, welche durch gastritogene CD4+ T-Zellen verursacht wurde, deren Aktivierung auch unabhängig von Lymphknoten und TLOs erfolgte. Die Entstehung von TLOs wird auch bei einer durch Helicobacter pylori ausgelösten chronischen Gastritis beobachtet. Die Expression des homöostatischen Chemokinrezeptors CXCR5 und seines Liganden CXCL13 ist mit der Entwicklung dieser TLOs korreliert worden. Unter Verwendung eines Mausmodells für H. pylori-induzierte chronische Gastritis konnte gezeigt werden, dass CXCR5 die Ausbildung von TLOs vermittelt und eine Rolle für die Induktion von H. pylori-spezifischen T-Zell- sowie humoralen Immunantworten spielt. / Homeostatic recirculation of immune cells through peripheral and secondary lympoid organs (SLOs) is required for immune surveillance and the maintenance and functionality of the immune system. The homeostatic chemokine receptor CCR7 controls not only lymphoid cell trafficking to and within SLOs, but also seems to be involved in the homeostatic recirculation of lymphocytes through non-lymphoid peripheral tissues. Within the scope of this work we investigated the functional relevance of CCR7 for the homeostatic recirculation of lymphocytes through the peritoneal cavity and could show, that CCR7 is the dominant chemokine receptor which defines the transit time of lymphocytes in the peritoneal cavity under physiological conditions. Impaired recirculation of lymphocytes also promoted the development of tertiary lymphoid organs (TLOs) in the gastric mucosa of CCR7-deficient mice. Analysis of the cellular and molecular mechanisms underlying these and other pathomorphological alterations in the gastric mucosa of CCR7-deficient mice provided further evidence regarding the function of CCR7 for the establishment of central and peripheral tolerance towards gastric antigens. Mice that lack CCR7 spontaneously developed autoimmune gastritis, which was caused by gastritogenic CD4+ T-cells. Such autoreactive T cell responses were also initiated in the absence of lymph nodes and TLOs in CCR7/LT-alpha double-deficient mice. Development of TLOs is also observed during chronic gastritis induced by Helicobacter pylori. The expression of the homeostatic chemokine receptor CXCR5 and its ligand CXCL13 has been correlated with the development of these TLOs. Using a mouse model for H. pylori-induced chronic gastritis, we could show that CXCR5 is responsible for the development of TLOs and also plays a role for the induction of H. pylori-specific T and B cell responses.

Made available in DSpace on 2015-02-24T17:42:52Z (GMT). No. of bitstreams: 1 ThalesRFP_DISSERT.pdf: 5363462 bytes, checksum: 16f2d3a123870a2d8c63de00ac4bf689 (MD5) Previous issue date: 2014-02-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Helicobacter pylori is the main cause of gastritis, gastroduodenal ulcer disease and gastric cancer. The most recommended treatment for eradication of this bacteria often leads to side effects and patient poor compliance, which induce treatment failure. Magnetic drug targeting is a very efficient method that overcomes these drawbacks through association of the drug with a magnetic compound. Such approach may allow such systems to be placed slowed down to a specific target area by an external magnetic field. This work reports a study of the synthesis and characterization of polymeric magnetic particles loaded with the currently used antimicrobial agents for the treatment of Helicobacter pylori infections, aiming the production of magnetic drug delivery system by oral route. Optical microscopy, scanning electron microscopy, transmission electron microscopy, x-ray powder diffraction, nitrogen adsorption/desorption isotherms and vibrating sample magnetometry revealed that the magnetite particles, produced by the co-precipitation method, consisted of a large number of aggregated nanometer-size crystallites (about 6 nm), creating superparamagnetic micrometer with high magnetic susceptibility particles with an average diameter of 6.8 ? 0.2 μm. Also, the polymeric magnetic particles produced by spray drying had a core-shell structure based on magnetite microparticles, amoxicillin and clarithromycin and coated with Eudragit? S100. The system presented an average diameter of 14.2 ? 0.2 μm. The amount of magnetite present in the system may be tailored by suitably controlling the suspension used to feed the spray dryer. In the present work it was 2.9% (w/w). The magnetic system produced may prove to be very promising for eradication of Helicobacter pylori infections / A Helicobacter pylori ? a principal causa de gastrites, ?lceras gastroduodenais e c?ncer g?strico. O esquema terap?utico de primeira escolha para a erradica??o desse pat?geno leva muitas vezes a elevado n?mero de rea??es adversas, baixa ades?o do paciente e consequentemente falha na terap?utica. A vetoriza??o magn?tica ? uma t?cnica bastante difundida na literatura que visa minimizar esses problemas, atrav?s da associa??o de f?rmacos a n?cleos magn?ticos direcionando para o local de a??o por interm?dio de campo magn?tico externo. O presente trabalho relata o estudo da s?ntese e caracteriza??o de part?culas polim?ricas magn?ticas contendo os mais frequentes antimicrobianos (amoxicilina e claritromicina) usados no tratamento de infec??es por Helicobacter pylori, objetivando a produ??o de um sistema para vetoriza??o magn?tica por via oral. Granulometria baseada no di?metro de Feret, microscopia eletr?nica de varredura e transmiss?o, difratometria de raio-x, isotermas de adsor??o/dessor??o de nitrog?nio e magnetometria de amostra vibrante revelaram que as part?culas de magnetita, produzidas pelo m?todo da coprecipita??o, consistem em grande n?mero de agregados de cristalitos de tamanhos nanom?tricos (da ordem de 6 nm) os quais formam part?culas microm?tricas superparamagn?ticas de alta susceptibilidade magn?tica, tendo formato irregular com di?metro m?dio de 6,8 ? 0,2 μm. Os n?cleos magn?ticos foram revestidos por pol?mero (Eudragit? S100) em conjunto com amoxicilina e claritromicina (forma polim?rfica II) sendo obtido micropart?culas n?cleo-camada de formato irregular, pela t?cnica de secagem por aspers?o (spray dryer), com um di?metro m?dio de 14,2 ? 0,2 μm. A quantidade de magnetita presente no sistema pode ser adaptada pelo controle da suspens?o inicial usada na alimenta??o do spray dryer. No presente trabalho o conte?do magn?tico final foi estimado em 2,9 % (p/p). Com base nos resultados obtidos, o sistema magn?tico produzido pode se tornar bastante promissor na erradica??o de infec??es por Helicobacter pylori

Atualmente, muitas são as diretrizes na literatura quanto à influência do Helicobacter pylori na Doença do Refluxo Gastroesofágico. Alguns autores acreditam que o H. pylori poderia ter um efeito protetor para o desenvolvimento na DRGE e outros até mesmo concluem que o agente possa ser um fator agravante na doença. Muitas publicações nos alertam para o desenvolvimento de sintomas da DRGE, ou mesmo da esofagite, em uma porcentagem razoável de pacientes erradicados pelo esquema tríplice para tratar o H. pylori, sendo que aproximadamente 10% teriam DRGE. Na verdade, por essas dúvidas, ainda não foi estabelecido um consenso quanto à importância do H. pylori na etiopatogenia da DRGE e suas complicações. Fato também discutido, seria a importância das cepas para a formação da esofagite em pacientes submetidos à erradicação. Talvez as mais virulentas, assim como a presença da “ilha de patogenicidade”(cagA) ou algumas cepas vacuolizantes (vacA), teriam uma maior relação com a prevenção da esofagite. Outro mecanismo importante, apontado por muitos, para a formação da esofagite em pacientes erradicados seria a elevação do índice de Massa Corpórea nesse grupo de pacientes erradicados associados ou não à presença da hérnia hiatal e justificados pela melhor qualidade de vida após melhora dos sintomas depois da erradicação. Em nosso estudo, 148 pacientes com úlcera péptica ativa ou cicatrizada receberam esquema tríplice de erradicação para o Helicobacter pylori e foram submetidos a exame endoscópico e ao teste histopatológico das amostras colhidas por biópsias de corpo e antro, teste respiratório com Carbono 14 e urease, antes e após o tratamento. Realizamos a genotipagem do agente, através do PCR, separando amostras de corpo e de antro, para determinar as cepas do agente. Os pacientes foram seguidos ambulatorialmente por um ano e avaliados quanto à melhora ou piora dos sintomas relacionados a DRGE (pirose) e sintomas considerados inespecíficos como a dor epigástrica; também procuramos quantificar o ganho ou perda do IMC. Encontramos 28 pacientes (18,9%) com esofagite erosiva (24 grau A e 4 grau B de Los Angeles) endoscópica após o tratamento do agente. Deste grupo, somente 3 pacientes que não tinham sintomas desenvolveram pirose (2%). A grande maioria dos pacientes se beneficiou com o tratamento, mostrando que 69 46,6%) melhoraram da pirose e outra grande maioria melhorou dos sintomas inespecíficos. Em 18 pacientes ulcerosos com esofagite, a análise de fragmentos de corpo foi cagA positiva (64,3%) e em amostras de antro 21 eram cagA positivos (75%). Assim como no grupo geral, as cepas vacuolizantes s1b/m1 e s1b foram, respectivamente, as mais encontradas no grupo da esofagite endoscópica. Houve ligeiro aumento nos Índices de Massa Corpórea em pacientes com e sem esofagite, sendo estatisticamente mais significativo nos 120 pacientes sem esofagite. Apesar do aparecimento da esofagite erosiva endoscópica em número razoável de pacientes, a sintomatologia não foi fator determinante, pois muitos melhoraram dos sintomas após o tratamento, e a erradicação não foi importante para determinar o grau de esofagite erosiva. Não foi encontrada nenhuma relação entre a genotipagem do agente e o desenvolvimento de esofagite endoscópica. O aumento de IMC, também não justifica, em nosso estudo a esofagite em pacientes ulcerosos tratados contra o H. pylori. / Nowadays, there are many directrixes in literature as to the influence of Helicobacter pylori, in the Disease of Gastroesophagic reflux. Some authors believe that H. pylori could have a protective effect to the development of GERD, and others even conclude that the agent may be an aggravating factor in the disease. Many publications allert us to the development of symptoms of GERD, or even the esophagitis,in a reasonable percentage of erradicated patients by the triplicit scheme to treat H. pylori, and 10%, approximately, would have GERD. In fact, due to these doubts, a consensus has not been established yet to the importance of H. pylori in the GERD’s etiopathogenic and its complications. The strains importance to the formation of esophagitis in patients submitted to erradication is another fact that has also been discussed. Maybe the most virulent ones, as the presence of “pathogenical island”(cagA) or some other vacuolating cytotoxin (vacA), would have a larger relation in the esophagitis prevention. Another important mechanism, pointed by many, to the formation of esophagitis in erradicated patients would be the elevation of Body Mass Index in this group of eradicated patients associated or not to the presence of hiatal hernia and justified by a better quality of life due to symptoms’ improvement after erradication. In our studies, 148 patients with active or healed peptic ulcer received triplicit scheme of erradication to the Helicobacter pylori and were submitted to endoscopic exams and histopathologic test of gathered samples by body and antro biopsies, respiratory test with carbon 14 and ureasis, before and after treatment. We have done the agent genotyping, through the PCR, separating samples of body and antro, to determine the agent Cepas. The patients have been followed ambulatorially for a year and evaluated as to the improvement or worsening of the symptoms related to GERD (pyrosis) and symptoms considered non-specific as epigastric pain; we have also tried to quantify the gain or loss of Body Mass Index. We found 28 patients(18.9%) with endoscopic erosive esophagitis (24 degree A and 4 degree B of Los Angeles) after agent’s treatment. In this group, only three patients who had no symptoms developed pyrosis (2%). Most of the patients benefitted from treatment showing that 69 (46.6%) presented improvement in pyrosis and another great majority improved non-specific symptoms. In 18 ulcered patients with esophagitis, the body analysis fragments was positive cagA (64.3%)and in antro samples of 21 were positive cagA (75%). As in the general group, the vacuolizing cepas slb/ml and slb were, respectivelly, the most found in the endoscopic esophagitis group. There was a slight raise in the BMI in patients with and without esophagitis, and it is, statistically more meaningful in the 120 patients without esophagitis. Even though there was the appearance of endoscopic erosive esophagitis in a reasonable number of patients, the symptmology was not a determining factor, because many have got better after the treatment, and erradication was not important to determine the erosive esophagitis. It was not found any relation between the agent genotyping and the development of endoscopic esophagitis. The raise of BMI does not justify in our study the esophagitis in ulcered patients treated against H. pylori.