Host-pat hogen interactions during infection : a systems biology approach

Els continguts d'aquesta tesi estan enfocats en les interaccions entre un hoste-patogen durant un procés infectiu, per poder arribar a millorar el coneixement sobre les infeccions bacterianes i donar un punt de vista diferent per al disseny i síntesi d'antibiòtics. Primerament, vam fer un estudi comparatiu de l'interactoma de Yersinia pestis-Homo sapiens i el Yersinia pestis, on vam poder relacionar que el número d'interaccions d'una proteïna en l'interactoma Y.pestis-Homo sapiens es pot relacionar amb la importància d'aquella proteïna, essent així més essencials les que tenen més interaccions. A més a més, aquest resultat es pot associar a la regla "Centrality-lethality", que diu que les proteïnes més connectades en una cèl·lula són les més importants per a la seva supervivència. Seguidament es van fer diferents estudis en els quals es suprimia un nombre determinat de nodes i s'observava els canvis en la xarxa d'interaccions hoste-patogen, que ens va permetre correlacionar que les proteïnes altament connectades també tenen un alt impacte amb la supervivència de l'organisme durant la infecció. Aquesta relació obre una nova visió sobre l'estudi de les interaccions proteïna-proteïna durant un procés infectiu, que a la llarga es pot fer servir per al desenvolupament de nous fàrmacs. Per altra banda, s'ha estudiat les interaccions proteïna-proteïna durant un procés infectiu de cèl·lules epitelials humanes i el bacteri Acinetobacter baumannii, ja que els darrers anys aquest bacteri s'ha convertit en un bacteri amb una alta capacitat d'adquirir resistència als antibiòtics i causar moltes infeccions adquirides en els hospitals. Per això, es considerà molt important conèixer com aquest bacteri és capaç de sobreviure dintre d'una cèl·lula hoste. En primer lloc, vam voler comprovar la capacitat del bacteri de sobreviure i replicar dins de la cèl·lula hoste, i a més a més, vam validar la seva capacitat de controlar-la. En comprovar que aquest bacteri és capaç d'infectar i penetrar la cèl·lula hoste ens fa veure clarament avantatges davant de la resistència als antibiòtics actuals. Seguidament, vam voler estudiar les interaccions proteïna-proteïna per saber quines són les proteïnes que més interaccionen d'Acinetobacter baumannii que en un futur es podrien utilitzar com a diana pel disseny de nous medicaments. Com a conclusió general, aquesta tesi pretén donar noves perspectives sobre les malalties infeccioses. Estudiant les interaccions proteïna-proteïna durant la infecció, podem obrir nous camps de recerca i millorar el coneixement de les infeccions.Los contenidos de esta tesis están enfocados en las interacciones entre un huésped-patógeno durante un proceso infectivo, para poder mejorar el conocimiento sobre las infecciones bacterianas y dar un punto de vista diferente para el diseño y síntesis de antibióticos. Primeramente, se hizo un estudio comparativo del interactoma de Yersinia pestis-Homo sapiens y el Yersinia pestis, donde pudimos relacionar que el número de interacciones de una proteína en el interactoma Y.pestis-Homo sapiens puede relacionarse con la importancia de aquella proteína, siendo así más esenciales las que tienen más interacciones. Además, este resultado se puede asociar a la regla "centrality-lethality", que dice que las proteínas más conectadas en una célula son las más importantes para su supervivencia. Seguidamente se hicieron diferentes estudios en los que se suprimía un número determinado de nodos y observaba los cambios en la red de interacciones huésped-patógeno, que nos permitió correlacionar que las proteínas altamente conectadas también tienen un alto impacto con la supervivencia del organismo durante la infección. Esta relación abre una nueva visión sobre el estudio de las interacciones proteína-proteína durante un proceso infectivo, que a la larga se puede usar para el desarrollo de nuevos fármacos. Por otro lado, se ha estudiado las interacciones proteína-proteína durante un proceso infectivo de células epiteliales humanas y la bacteria Acinetobacter baumannii, ya que los últimos años esta bacteria se ha convertido en una bacteria con una alta capacidad de adquirir resistencia a los antibióticos y causar muchas infecciones adquiridas en los hospitales. Por ello, se consideró muy importante conocer cómo esta bacteria es capaz de sobrevivir dentro de una célula huésped. En primer lugar, quisimos comprobar la capacidad de la bacteria de sobrevivir y replicarse dentro de la célula huésped, y además, hicimos validar su capacidad de controlarla. Al comprobar que esta bacteria es capaz de infectar y penetrar la célula huésped nos hace ver claramente ventajas frente a la resistencia a los antibióticos actuales. Seguidamente, quisimos estudiar las interacciones proteína-proteína para saber cuáles son las proteínas que más interaccionan de Acinetobacter baumannii que en un futuro se podrían utilizar como diana para el diseño de nuevos medicamentos. Como conclusión general, esta tesis pretende dar nuevas perspectivas sobre las enfermedades infecciosas. Estudiando las interacciones proteína-proteína durante la infección, podemos abrir nuevos campos de investigación y mejorar el conocimiento de las infecciones.This thesis is focused on interactions between a host-pathogen during an infection process to improve the knowledge about bacterial infections and give a different perspective on the design and synthesis of new antibiotics. First, we compare Yersinia pestis-Homo sapiens with Yersinia pestis interactome and we could relate the number of interactions of a protein with the percentage of essential protein. So, the proteins with more interacting nodes are the more essential proteins in the host-pathogen interactome. Moreover, this result can be associated with the "Centrality-lethality" rule, which states that the most connected proteins in a cell are the most important for their survival. Finally, we attack a particular node of the host-pathogen interactome to see the effect in the host-pathogen network. From these calculations, we revealed that a centrality-based attack was the most effective in disrupting the global topological efficiency. This conclusion allowed us to correlate that highly connected proteins also have a high impact on the fitness of the organism during infection. This relationship opens up a new perspective on the study of protein-protein interactions during an infectious process, which can eventually be used for the development of new drugs. On the other hand, we studied protein-protein interactions during an infectious process of human epithelial cells and Acinetobacter baumannii. Recently, this bacterium has emerged as one of the most important drug-resistance responsible for hospital-acquired infections. Therefore, there is an urgent need to study and understanding how this bacterium can survive inside a host cell. Initially, we proved the ability of the bacterium to survive and replicate inside the host cell. In addition, we validated its ability to control the host cell. A.baumannii has an intercellular lifestyle that gives clear advantages over antibiotic resistance. Later, we determined the protein-protein interactions network to identify hub proteins and in the future, can be used as a target for developing new antimicrobials. As a general conclusion, this thesis aims to give new perspectives on infectious diseases. By studying protein-protein interactions during infection, opening up new fields of research, and understand infections at different levels of complexity

Time-Resolved Transcriptional Profiling of Epithelial Cells Infected by Intracellular Acinetobacter baumannii

Altres ajuts: European Society of Clinical Microbiology and Infectious Diseases Research Grant 2016The rise in the number of antibiotic-resistant bacteria has become a serious threat to health, making it important to identify, characterize and optimize new molecules to help us to overcome the infections they cause. It is well known that Acinetobacter baumannii has a significant capacity to evade the actions of antibacterial drugs, leading to its emergence as one of the bacteria responsible for hospital and community-acquired infections. Nonetheless, how this pathogen infects and survives inside the host cell is unclear. In this study, we analyze the time-resolved transcriptional profile changes observed in human epithelial HeLa cells after infection by A. baumannii, demonstrating how it survives in host cells and starts to replicate 4 h post infection. These findings were achieved by sequencing RNA to obtain a set of Differentially Expressed Genes (DEGs) to understand how bacteria alter the host cells' environment for their own benefit. We also determine common features observed in this set of genes and identify the protein-protein networks that reveal highly-interacted proteins. The combination of these findings paves the way for the discovery of new antimicrobial candidates for the treatment of multidrug-resistant bacteria

Centrality in the host-pathogen interactome is associated with pathogen fitness during infection

To perform their functions proteins must interact with each other, but how these interactions influence bacterial infection remains elusive. Here we demonstrate that connectivity in the host-pathogen interactome is directly related to pathogen fitness during infection. Using Y. pestis as a model organism, we show that the centrality-lethality rule holds for pathogen fitness during infection but only when the host-pathogen interactome is considered. Our results suggest that the importance of pathogen proteins during infection is directly related to their number of interactions with the host. We also show that pathogen proteins causing an extensive rewiring of the host interactome have a higher impact in pathogen fitness during infection. Hence, we conclude that hubs in the host-pathogen interactome should be explored as promising targets for antimicrobial drug design.M.T.B. would like to acknowledge support from the Programa Ramón y Cajal (RYC-2012-09999). This study has been funded by the Ministerio de Economía y Competitividad (SAF2014-56568-R) and a Research Grant 2016 by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) both to M.T.B. N.S.d.G acknowledges support of the Spanish Ministry of Economy and Competitiveness, 'Centro de Excelencia Severo Ochoa 2013-2017' and CERCA Programme from the Generalitat de Catalunya

Centrality in the host-pathogen interactome is associated with pathogen fitness during infection

Altres ajuts: 'Centro de Excelencia Severo Ochoa 2013-2017' and CERCA Programme from the Generalitat de CatalunyaTo perform their functions proteins must interact with each other, but how these interactions influence bacterial infection remains elusive. Here we demonstrate that connectivity in the host-pathogen interactome is directly related to pathogen fitness during infection. Using Y. pestis as a model organism, we show that the centrality-lethality rule holds for pathogen fitness during infection but only when the host-pathogen interactome is considered. Our results suggest that the importance of pathogen proteins during infection is directly related to their number of interactions with the host. We also show that pathogen proteins causing an extensive rewiring of the host interactome have a higher impact in pathogen fitness during infection. Hence, we conclude that hubs in the host-pathogen interactome should be explored as promising targets for antimicrobial drug design. Hubs tend to be essential for function in protein networks within organisms. Here, the authors show that during infection, it is the proteins with high centrality in the Y. pestis host-pathogen interactome that are most important for pathogen fitness during infection, and highlight the importance of pathogen proteins that likely cause significant perturbation of the host interactome