This thesis focuses on two processes involved in fighting infections: metabolism and immune cell motility and navigation.Regarding metabolism, we present ZebraGEM 2.0, an improved whole-genome... Show moreThis thesis focuses on two processes involved in fighting infections: metabolism and immune cell motility and navigation.Regarding metabolism, we present ZebraGEM 2.0, an improved whole-genome scale metabolic reconstruction for zebrafish, that we used to study zebrafish metabolism upon infection with Mycobacterium marinum integrating gene expression data from control and infected zebrafish larvae. The chapters focusing on cell motility in response to the environment, revolve around the question of how the environmental inputs of cell-matrix interactions, cell-sized obstacles and cell-signalling upon wounding shape and guide cell motility. Show less
Metastatic cancer is aggressive and rapidly developing, making it difficult to treat, often leading to mortality. Cancer cells are not isolated, but rather survive and proliferate in complex tumor...Show moreMetastatic cancer is aggressive and rapidly developing, making it difficult to treat, often leading to mortality. Cancer cells are not isolated, but rather survive and proliferate in complex tumor microenvironments. Importantly, tumor cells “educate” immune cells to play a supportive role during cancer progression. Therefore, understanding how cancer cells and immune cells communicate is of pivotal importance to limit tumor progression. In this project, we identified the chemokine receptor CXCR4 and its correspondent ligand, CXCL12, as a key couple that regulate the interaction between tumor cells and immune cells. The research has been performed using the zebrafish xenograft model. This model offers the advantage of looking at tumor-immune cell interaction on a single cell level and in a living whole organism. The transparency of the embryo and the current genetic tools available, in combination with the ease in pharmacological approaches, make this model an excellent tool to determine and impair cancer-microenvironment inter-communication. We showed that inhibiting the CXCL12-CXCR4 axis either on the tumor side or on the immune cell side leads to impaired tumor progression, during the early phases of metastasis formation. We propose that blocking cancer-stroma communication represents a promising therapeutic strategy to fight cancer.Show less
Toll-like receptors (TLRs) are receptors that continuously scour their direct surroundings for pathogen associated molecular patterns (PAMPs) of bacterial, viral or fungal origin. TLRs can be found... Show moreToll-like receptors (TLRs) are receptors that continuously scour their direct surroundings for pathogen associated molecular patterns (PAMPs) of bacterial, viral or fungal origin. TLRs can be found at cells that play a role in the immune system. Binding of the TLR with its corresponding ligand results in a signaling cascade, which initially activates the innate immune system and can eventually result in activation of the adaptive immune system. When used as well-defined adjuvants, their combination with antigen may increase the immunogenicity of the antigen itself. This so-called vaccine principle may lead to a desired long-lasting adaptive immune response or humoral memory. Currently a total of 11 TLRs are known in humans and their specific PAMPs are directly related to the location where the receptor resides. TLRs 1, 2, 4, 5, 6, 10 and 11 are situated on the outside of the cell membrane, where they come into direct contact with membrane components of pathogens. TLRs 3, 7, 8 and 9 can be found intracellularly and their ligands mainly consist of viral components released after cellular uptake and degradation of the invader. A large diversity of natural and synthetic TLR ligands is available. The newest generation of vaccines is based on synthetic TLR ligands having a well-defined chemical structure. The research described in this thesis is a first step towards the development of well-defined vaccines, able to trigger a controlled immune response by means of using TLR 2, 7 or 9. Discussed in detail are the synthesis and the immunological evaluation of ligands and conjugates aimed at activation of Toll-like receptors 2, 7 and 9. Some examples are the synthesis of a CpG DNA-peptide conjugate (TLR 9), a Pam3Cys-peptide conjugate (TLR 2) and a 7-hydro-8-oxo-adenine-peptide conjugate (TLR 7). After synthesis of the peptide (containing the antigen), several methods were applied to conjugate it to TLR2, 7 and 9 ligands. Resulting from the research performed, is that when well chosen, covalent coupling of a TLR ligand with an antigenic peptide results in an increase of cytokine production as well as antigen presentation, two of the most desired characteristics of a synthetic vaccine of this class. It is not unlikely, that future synthetic vaccines will be sharing these properties. Show less
