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Diversity of CD8+ T-cell adaptive immune responses
Paprčková, Darina ; Štěpánek, Ondřej (advisor) ; Dobeš, Jan (referee) ; Gerrard, Audrey (referee)
CD8+ T cells are specialized immune cells that recognize and eliminate infected or malignant cells by directly attacking and destroying them. Moreover, their ability to form long-lasting memory responses ensures a rapid immune defense upon subsequent encounters with the same pathogens, making them indispensable for overall immune system function and maintaining health. Despite all of this, many aspects of their biology are still not well understood. The main objective of this thesis is to delve deeply into the adaptive immune responses of CD8+ T cells, focusing on elucidating several critical aspects. Firstly, we conducted a review and a research study of T-cell receptor (TCR) self-reactivity to understand its influence on immune responses. Intriguingly, experimental findings revealed that the degree of TCR self-reactivity did not impact the magnitude or type of the immune response. Instead, it played a decisive role in determining the fate commitment of CD8+ T cells in the periphery during homeostasis, shedding light on a nuanced regulatory mechanism. Another part of the research probed into per-cell differences of activated naïve and memory T cells. This investigation unveiled the remarkable potency of memory T cells to generate long- lived effector memory T cells. In contrast, naïve T cells...
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Mechanisms of the tolerance and homeostasis of immune cells
Tsyklauri, Oksana ; Štěpánek, Ondřej (advisor) ; Černý, Jan (referee) ; Froňková, Eva (referee)
The ability of the immune system to tolerate self-antigens while mounting appropriate responses to pathogens is indispensable for the survival of the organism. Despite years of research, many details of the mechanisms of self-tolerance are still not well understood. The objective of this thesis is to extend our knowledge of the mechanisms of immune tolerance. The core of the PhD thesis consists of five publications related to two main research directions. The first one addresses the mechanisms of peripheral immune tolerance established by regulatory T cells (Tregs). We showed that Tregs increase the quorum of self-reactive CD8+ T cells required for the induction of autoimmunity. In addition, we identified a novel subset of antigen-stimulated CD8+ T cells, which expand in the absence of Tregs. We called them super-effector T cells. We revealed that the administration of IL-2 phenocopies the absence of Tregs, i.e., it induces super- effector T cells, and enhances CD8+ T cell response in autoimmunity and cancer. Our results provide strong evidence that the major suppressive mechanism of Tregs is limiting IL-2 availability for CD8+ T cells. Furthermore, in a collaborative project, we have shown that MyD88 signaling in thymic epithelial cells contributes to the development of Tregs and thus to the...
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MHC class I allelic variability and pro-inflammatory responsiveness in domestic fowl breeds
Pojezdná, Anežka ; Vinkler, Michal (advisor) ; Hyršl, Pavel (referee)
Domestic fowl (Gallus gallus f. domestica) is an economically important model species in science. Knowledge of the immune system of this species is therefore crucial. In research the commercial stocks are usually used together with laboratory inbred lines. They have an unnatural variability, as a result of inbreeding, their genetic and phenotypic variability is reduced. This laboratory lines are therefore not the best model for research of variability. Presently, genetically diversified poultry populations can be found in rural stocks and fancy breeds. These breeds could be good model for research in variability of immunoresponse. In this thesis, I try to map the genetic variability of the binding site of MHC class I glycoproteins in fowl breeds. In chickens are these molecules encoded in duplicated gene called BF (BF1 and BF2). These genes are relatively well known and considerable variability has been described in domestic fowl. Our results suggest a high genetic variability of MHC I in domestic fowl breeds. We had identified 41 haplotypes in 25 individuals of 14 breeds, including 7 haplotypes already known from the literature. I also focused on proinflammatory activity in fowl breeds. I watched swelling of tissue and expression of pro-inflammatory cytokines IL-6 and IL-1 after subcutaneous...
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Role of CD8- and CD4-Lck interactions in the signaling and development of T cells.
Horková, Veronika
Adaptive immune response plays a key role in maintaining homeostasis of the organism. T cells use an immense repertoire of T-cell receptors (TCRs) to discriminate between self and foreign antigens with very high sensitivity. Although we have many clues outlining how an ideal TCR repertoire is selected, and a good understanding of the TCR signaling machinery, there are still some key aspects of these processes that remain controversial. The objective of this thesis is to extend our knowledge of the very proximal events of TCR signaling, with special focus on interaction of TCR coreceptors with lymphocyte-specific kinase LCK. Coreceptor-LCK interaction has been described to regulate several aspects of T- cell development and response. We observed dynamic change of this interaction in course of T-cell development. Interestingly, CD4 and CD8 coreceptors displayed differential dynamics of interaction with LCK. Our data suggest that such disparity in coreceptor- LCK interaction leads to selection of more self-reactive TCR repertoire in CD8+ T cells. Moreover, when the highly self-reactive CD8+ T cells get to the periphery, the homeostatic signals drive their differentiation towards a more tolerogenic memory-like phenotype. To finally resolve the role of coreceptor-LCK interaction in the T-cell...
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Role of CD8- and CD4-Lck interactions in the signaling and development of T cells.
Horková, Veronika ; Štěpánek, Ondřej (advisor) ; Černý, Jan (referee) ; Hons, Miroslav (referee)
Adaptive immune response plays a key role in maintaining homeostasis of the organism. T cells use an immense repertoire of T-cell receptors (TCRs) to discriminate between self and foreign antigens with very high sensitivity. Although we have many clues outlining how an ideal TCR repertoire is selected, and a good understanding of the TCR signaling machinery, there are still some key aspects of these processes that remain controversial. The objective of this thesis is to extend our knowledge of the very proximal events of TCR signaling, with special focus on interaction of TCR coreceptors with lymphocyte-specific kinase LCK. Coreceptor-LCK interaction has been described to regulate several aspects of T- cell development and response. We observed dynamic change of this interaction in course of T-cell development. Interestingly, CD4 and CD8 coreceptors displayed differential dynamics of interaction with LCK. Our data suggest that such disparity in coreceptor- LCK interaction leads to selection of more self-reactive TCR repertoire in CD8+ T cells. Moreover, when the highly self-reactive CD8+ T cells get to the periphery, the homeostatic signals drive their differentiation towards a more tolerogenic memory-like phenotype. To finally resolve the role of coreceptor-LCK interaction in the T-cell...
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Characterization of T-cell clones from naïve and virtual memory compartment
Přibíková, Michaela ; Štěpánek, Ondřej (advisor) ; Drbal, Karel (referee)
Virtual memory (VM) CD8+ T cells represent a population of antigen-inexperienced T cells with an apparent memory phenotype. In lymphoreplete germ-free mice VM CD8+ T cells represent 10-20% of all peripheral CD8+ T cells. Their origin correlates with the levels of self-reactivity where the main factor that determinates the T-cell fate decision is the strength of homeostatic signals. In the first part of this thesis, we demonstrated that VM CD8+ T cells and naïve CD8+ T cells had distinct TCR repertoire and T-cell subsets contained different clonotypes. Moreover, 'VM clones' were enriched among VM T cells and were also present in naïve T cells. In contrast, 'naïve clones' were almost exclusively detected in naïve T cells. Next, we characterized the signaling of particular OVA-reactive TCRs from both naïve and VM subsets. We confirmed that 6 out of 8 tested TCRs were responsive to Kb-OVA. In the last part of the thesis, we developed and optimized a qPCR-based method for the relative quantification of specific T-cell clonotypes prior to and during the immune response. This method will serve as a tool for studying the biology of particular VM and naïve T-cell subsets and their role during the immune response. Keywords: T-cell receptor, homeostatic signaling, self-reactivity, virtual memory cells, T cells
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MHC class I allelic variability and pro-inflammatory responsiveness in domestic fowl breeds
Pojezdná, Anežka ; Vinkler, Michal (advisor) ; Hyršl, Pavel (referee)
Domestic fowl (Gallus gallus f. domestica) is an economically important model species in science. Knowledge of the immune system of this species is therefore crucial. In research the commercial stocks are usually used together with laboratory inbred lines. They have an unnatural variability, as a result of inbreeding, their genetic and phenotypic variability is reduced. This laboratory lines are therefore not the best model for research of variability. Presently, genetically diversified poultry populations can be found in rural stocks and fancy breeds. These breeds could be good model for research in variability of immunoresponse. In this thesis, I try to map the genetic variability of the binding site of MHC class I glycoproteins in fowl breeds. In chickens are these molecules encoded in duplicated gene called BF (BF1 and BF2). These genes are relatively well known and considerable variability has been described in domestic fowl. Our results suggest a high genetic variability of MHC I in domestic fowl breeds. We had identified 41 haplotypes in 25 individuals of 14 breeds, including 7 haplotypes already known from the literature. I also focused on proinflammatory activity in fowl breeds. I watched swelling of tissue and expression of pro-inflammatory cytokines IL-6 and IL-1 after subcutaneous...
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Intracellular life of pathogenic bacterium Francisella tularensis in the host.
Rädisch, Robert ; Konopásek, Ivo (advisor) ; Vopálenská, Irena (referee)
Francisella tularensis is a facultative intracellular pathogenic bacterium, which causes disease named tularemia. For the entrance to the host cells Francisella uses host's cell mechanisms by which it is incorporated into cell phagosome. Subsequently, it escapes from phagosome to cytosole where bacterial growth takes place. Some of bacteria are cleared from cytosol by autophagy, from another ones dsDNA is released. This DNA is recognized by cytosolic receptors, which form inflammasome complex. Inflammasome sets off pathway leading to the death of infected cell. Since the penetration to the cell Francisella modulates cell signallization in its own benefit to ensure enough time and nutrients for its growth. Francisella do not act only in the infected cells, where it reduces recognition of itself and clearance from cytosol, but it also induces secretion of factors, which moderate activation of adaptive immunity of the host. Key words: Francisella, tularemia, fagosome, inflammasome, autophagy, adaptive immunity
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