This thesis is focused on the innate immune defence mechanisms responsible for controlling mycobacterial growth after infection. To provide a detailed description of the host__s innate immune... Show moreThis thesis is focused on the innate immune defence mechanisms responsible for controlling mycobacterial growth after infection. To provide a detailed description of the host__s innate immune response to M. marinum infection, zebrafish gene expression levels were analysed by RNA sequencing at various time points during infection and correlated with imaging data of the process of pathogenesis. We demonstrate that the scavenger receptor Marco (macrophage receptor with collagenous structure) is a key player in the rapid phagocytosis of M. marinum and we use gene expression analysis in combination with gene knockdown studies to show that it is also essential in the establishment of an initial transient pro-inflammatory response to M. marinum infection. Once phagocytosed, M. marinum is capable of avoiding killing mechanisms of the host cell and can continue to grow within macrophages. This is the period when Membrane Attack Complex/Perforin proteins are involved in killing intracellular bacteria by their pore-forming activities. We reveal the regulatory mechanisms and function of two macrophage specific genes, mpeg1 and mpeg1.2 (macrophage expressed gene 1.2). The results from this thesis complement knowledge obtained from other model organisms by providing new insights into both counteracting and supporting mechanisms underlying the innate immune response. Show less
Alpha1-antitrypsin is an important neutrophil elastase inhibitor that protects lung tissue from the destructive effects of neutrophil elastase released by degranulating neutrophils. In addition to... Show moreAlpha1-antitrypsin is an important neutrophil elastase inhibitor that protects lung tissue from the destructive effects of neutrophil elastase released by degranulating neutrophils. In addition to the liver, local production by macrophages and airway and alveolar epithelial cells may contribute to the formation of an anti-elastase screen in the lung. The Z mutation (E342K) of _1-antitrypsin, compromising over 95% of the _1-antitrypsin deficiency patients, causes subtle misfolding of the protein that permits polymer formation and accumulation within the endoplasmic reticulum (ER) of hepatocytes leading to plasma deficiency. This causes hepatic cirrhosis and early-onset lung emphysema. The discovery of ZZ polymers in broncho-alveolar lavage fluid and pulmonary tissue and their identification many years after liver transplantation led to the proposal that pulmonary pathology could be induced by polymers. Overexpression of Z _1-antitrypsin is known to induce polymer formation, prime cells for an exaggerated ER stress response upon a second hit and initiate NF-_B signalling. However, whether endogenous expression in primary bronchial epithelial cells and monocyte-derived macrophages has similar consequences remained unclear. This thesis concentrate on these specific questions. In addition, we focused on the ER stress response induced by P.aeruginosa as a possible second hit in _1-antitrypsin deficiency Show less
