Pathogenic Neisseria Hitchhike on the Uropod of Human Neutrophils

Polymorphonuclear neutrophils (PMNs) are important components of the human innate immune system and are rapidly recruited at the site of bacterial infection. Despite the effective phagocytic activity of PMNs, Neisseria gonorrhoeae infections are characterized by high survival within PMNs. We reveal a novel type IV pilus-mediated adherence of pathogenic Neisseria to the uropod (the rear) of polarized PMNs. The direct pilus-uropod interaction was visualized by scanning electron microscopy and total internal reflection fluorescence (TIRF) microscopy. We showed that N. meningitidis adhesion to the PMN uropod depended on both pilus-associated proteins PilC1 and PilC2, while N. gonorrhoeae adhesion did not. Bacterial adhesion elicited accumulation of the complement regulator CD46, but not I-domain-containing integrins, beneath the adherent bacterial microcolony. Electrographs and live-cell imaging of PMNs suggested that bacterial adherence to the uropod is followed by internalization into PMNs via the uropod. We also present data showing that pathogenic Neisseria can hitchhike on PMNs to hide from their phagocytic activity as well as to facilitate the spread of the pathogen through the epithelial cell layer

Influence of probiotic treatment on allergy methylomics : Gene network analysis of epigenetic methylation patterns in CD4+ T cells from newborns treated with Lactobacillus reuteri

The composition and diversity of the gastrointestinal microbiota and its interaction with human cells have been frequently associated with immune system functions and disease development, including autoimmunity and allergy. This is believed to be mediated in part through epigenetic modifications, mainly as DNA methylation. Several studies have collectively supported the beneficial effects of probiotics for the prevention of allergic disease. However, there have been few studies addressing the possibility for probiotic supplementation to induce epigenetic changes and its importance for allergy development. This study aims to investigate whether probiotic treatment with Lactobacillus reuteri, distributed during and after the pregnancy period, leads to epigenetic changes in the offspring and if this have any effect on the development of allergic disease. DNA methylation data received from a clinical allergy prevention study was analysed through a set of bioinformatics methods and basic network analysis. The obtained results suggests that supplementation with L. reuteri indeed induces some significant changes in DNA methylation. These changes did not exhibit any significant correlation with allergy outcome of the children. Furthermore, the methylation changes were found at positions located in genes not enriched for any allergy-related biological pathways. However, when taking the genes interactions with other genes into account an interconnected gene interaction module could be identified that showed enrichment for biological processes involved in the T cell receptor signaling pathway, central for immune response transduction. Further analyses did not fit into the time-frame of this thesis, but the obtained results gives a first informative view of the effects of L. reuteri on methylation patterns, and points out directions for the continuing project work

The Complex Genetics of Multiple Sclerosis : A preliminary study of MS-associated SNPs prior to a larger genotyping project

Biomedical research have been revolutionized by recent technological advances, both in the fields of molecular biology and computer science, turning the biomolecular and genetic research into “big data science”. One of the main objectives have been to improve our understanding of complex human diseases. Among those diseases, multiple sclerosis (MS) is considered as one of the most common. MS is a chronic autoimmune disease that cause inflammation and damage to the central nervous system. In this study, a set of bioinformatics analyses have been conducted on SNP data, as an initial step to gain more information prior to an upcoming genotyping project. The results showed extensive regulatory properties for the 761 selected SNPs, which is consistent with current scientific knowledge, and also identified another 332 SNPs in linkage to these. However, during the study some issues have also been identified, which need to be addressed going forward

Influence of probiotic treatment on allergy methylomics : Gene network analysis of epigenetic methylation patterns in CD4+ T cells from newborns treated with Lactobacillus reuteri

The composition and diversity of the gastrointestinal microbiota and its interaction with human cells have been frequently associated with immune system functions and disease development, including autoimmunity and allergy. This is believed to be mediated in part through epigenetic modifications, mainly as DNA methylation. Several studies have collectively supported the beneficial effects of probiotics for the prevention of allergic disease. However, there have been few studies addressing the possibility for probiotic supplementation to induce epigenetic changes and its importance for allergy development. This study aims to investigate whether probiotic treatment with Lactobacillus reuteri, distributed during and after the pregnancy period, leads to epigenetic changes in the offspring and if this have any effect on the development of allergic disease. DNA methylation data received from a clinical allergy prevention study was analysed through a set of bioinformatics methods and basic network analysis. The obtained results suggests that supplementation with L. reuteri indeed induces some significant changes in DNA methylation. These changes did not exhibit any significant correlation with allergy outcome of the children. Furthermore, the methylation changes were found at positions located in genes not enriched for any allergy-related biological pathways. However, when taking the genes interactions with other genes into account an interconnected gene interaction module could be identified that showed enrichment for biological processes involved in the T cell receptor signaling pathway, central for immune response transduction. Further analyses did not fit into the time-frame of this thesis, but the obtained results gives a first informative view of the effects of L. reuteri on methylation patterns, and points out directions for the continuing project work

Exploring the tissue-specific nature of the Wnt cell signaling system : The complex world of cell communication and the search for the Achilles heel of cancer

The Wnt signaling pathway is a biological mechanism for cell-cell communication found across all species of the animal kingdom. This pathway plays a major role in virtually all stages of embryonic development, and it governs central aspects of stem cell biology, regeneration, and tissue homeostasis. In addition, dysregulation of the pathway is associated with developmental malformations and several forms of sever cancer. However, it is still not fully understood how Wnt signaling can mediate such a variety of processes and outcomes. How is a single pathway, which according to the current models is described as a mostly linear cascade of events, able to induce diverging responses in different biological contexts? Finding an answer to this question would not only satisfy scientific curiosity but could also have clinical significance. Given the importance of Wnt signaling in normal tissue function, therapeutically targeting the pathway has historically proven to be difficult. Thus, a better understanding of the tissue-specific properties of the pathway could help us uncover a way to distinguish disease-related cells from healthy cells and identify new targets whose inhibition could impair disease while avoiding detrimental effects on normal tissue function.        This thesis represents four years of research that aims to address the knowledge gaps outlined above. Specifically, the work has been focusing on exploring the time- and tissue-specific properties of Wnt signaling by assessing the genome-wide consequences of perturbing this pathway in different model systems. Through this work, we have revealed further instances of disconnection between classical Wnt components, challenging the current established models of how Wnt signaling operates. Furthermore, we demonstrate that the cellular response to Wnt activation occur in a time-dependent manner, with different responsive patterns in different cell types, and even heterogeneously across cells in an otherwise homogenous cell population, contributing to the emerging notion of context-specific Wnt signaling. Finally, we identify a new tissue-specific player in Wnt-mediated transcriptional regulation, which holds promise as a possible therapeutic target in the continuing battle against cancer.  In summary, the scientific results presented in this thesis extend our current knowledge of the Wnt signaling pathway by highlighting context-specific aspects that could help explain how this fundamental process adopts different regulatory avenues. This, in turn, could prove important for our ability to identify and ultimately combat disease-specific traits, including finding the Achilles heel of cancer.  

Ett maratonarbete : en trendstudie om konditionens förändring på tre olika svenska populationer

Syfte och frågeställningar   Syftet med uppsatsen är att undersöka GIH-studenters kondition och jämföra den trend som finns på GIH gentemot trender för konditionen hos mönstrande samt löpare i Stockholm Marathon. De frågeställningar som användes var: 1. Hur har GIH-studenters maximala syreupptagningsförmåga förändrats från 1977 till 2008? 2. Hur har mäns arbetskapacitet under mönstringen förändrats mellan åren 1969-83 samt 1986-93? 3. Hur har medeltiden förändrats för de löpare som deltog i och slutförde Stockholm Marathon mellan åren 1979-2008? Metod Dels deltog vi i framtagande av ny data i egenskaper av testledare i ett projekt för att undersöka GIH-studenters maximala syreupptagningsförmåga under hösten 2008 (n=28). Dessa data jämfördes sedan med tidigare framtagna data från ett liknande test på GIH-studenter från 1977 (n=44). Resterande del av undersökningen var bearbetning av befintlig data. Totalt studerades 183 216 löpare i Stockholm Marathon samt i snitt 45 000 mönstrande för varje studerat år. Resultat De resultat som framkom av studien var att en negativ utveckling gick att utläsa på GIH-studenternas maximala syreupptagningsförmåga, från 4,50 l O2/min hos männen till 4,24 l O2/min, medan utvecklingen hos kvinnorna var minimal, 2,88 l O2/min till 2,86 l O2/min. Utvecklingen blev större när korrelation mellan vikt och syreupptagningsförmåga gjorts, 61,6ml O2/min*min-1 till 55,6ml O2/min*min-1 för männen medan en förändring från 47,8ml O2/min*min-1 till 44,9ml O2/min*min-1 hos kvinnorna kunde konstateras. Hos mönstrande män var utvecklingen tvådelad; under åren 1969-83 ökade arbetskapaciteten per kilo kroppsvikt något, 3,53W/kg till 3,69W/kg, medan det skedde en minskning mellan 1986 och 1993; 4,34W/kg till 4,17W/kg. För löpare i Stockholm Marathon ökade sluttiden stadigt mellan 1979 och 2008 från att ha legat i medel på 215 min för herrar 1979 till 243 min 2008. Motsvarande tider för damer låg 1979 på 233 min för att stiga till 257 min 2008. Slutsats Utvecklingen för konditionen hos GIH-studenter ligger väl i linje med befintlig forskning som visar på en försämring hos den manliga delen hos befolkningen mot en svagt negativ eller oförändrad kondition hos kvinnorna. Denna trend går dock inte att utläsa på bearbetad mönstringsdata, vars förändring var för liten för att statistiskt kunna säkerställas. En tydlig försämring uppmättes av sluttiden i Stockholm Marathon vilket tros bero på en försämring i konditionen hos löparna. De framtagna resultaten bekräftas i stort av tidigare forskning som visar på en försämring av konditionen men samtidigt visar statistik på att träningsfrekvensen inte sjunkit. Därför drar vi slutsatsen att en annan typ av träning är mer vanligt förekommande idag, såsom koordinations- och styrketräning. Detta är dock inte säkerställt utan en slutsats baserad på forskningsläget.

Transport of organic chlorine through soil : A study of organic chlorine in soil water from a catchment in northern Sweden

Chlorine is an element commonly found in the environment of our planet, in the atmosphere, the earth crust and the oceans. Chlorine occurs in two forms, inorganic chloride (Clin) and organically bound chlorine (Clorg), also called organochlorine. For a long time, the organic halogens (among them the organic chlorine) had been considered as produced only by human activities. However, the research of the recent decades suggests a considerably amount of naturally produced organic chlorine in soil and water. Through the research, a hypothesis have emerged, suggesting that there occur a formation of organic chlorine in the top soil layer where chloride is consuming, while the organic chlorine is degrading on deeper soil levels, causing a release of chloride. The study in this thesis attempts to explore the transportation of organic chlorine through soil. 49 soil water samples were collected at three transects, S04, S12 and S22, nearby a stream in northern Sweden and analysed for Clorg, using an AOX-analyser. The results suggest a decrease in concentrations of Clorg by soil depth for transects S04 and S12. The study also indicates that concentrations of Clorg are decreasing with increasing distance from the stream, where the highest mean concentration was found in the organic matter-rich riparian transect S04. Further conclusions are that the spring flood and changes in groundwater level may influence the concentrations of Clorg.Ämnet klor är vanligt förekommande på vår planet och finns både i atmosfären, jordskorpan och världens oceaner. Klor uppträder i två olika former: oorganisk klorid (Clin) och organiskt bundet klor (Clorg). De organiska halogenerna (bland vilka organiskt klor ingår) har under lång tid ansetts härstamma från enbart antropogena källor. De senaste decenniernas forskning har dock tytt på en naturlig produktion av organiskt klor i mark och vatten. Genom denna forskning har en hypotes tagit form som föreslår en bildning av organiskt klor i de övre marklagren, där klorid binds, medan det i djupare marklager sker en nedbrytning av det organiska kloret vilket medför ett frigörande av klorid. Denna studie syftar till att studera transporten av organiskt klor genom mark. 49 stycken markvattenprover insamlades vid tre provpunkter (S04, S12 och S22) på ett avrinningsområde i norra Sverige och analyserades med hjälp av ett AOX-instrument. Resultaten tyder på en minskning av Clorg med ökande markdjup för provpunkterna S04 och S12. Studien visar även en minskning i koncentration av organiskt klor med ökande avstånd till vattendraget, där den högsta medelkoncentrationen återfanns i provpunkten S04 som ligger nära bäcken och är rik på organiskt material. Vidare slutsater är att vattenflödena under vårflod samt variasionen i grundvattennivå har en påverkan på koncentrationerna av Clorg