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The results presented in this thesis describe the investigation of Piscirickettsia salmonis derived membrane vesicles (MVs) as a vaccine candidate against salmonid rickettsial septicemia. MVs are small spherical structures known to contain a variety of bacterial components, including proteins, LPS, DNA and RNA, which makes the vesicles similar to their mother cell in many aspects. Comparative characterization of MVs from three different isolates of the bacterium revealed several strain specific differences, both in vivo and in vitro. When used for immunization in an adult zebrafish model the vesicles induced a protective response against P. salmonis. Incorporation of chitosan as an adjuvant, by MV encapsulation, did furthermore enhance the protective effect of the vesicles in adult zebrafish. Histological analysis indicated a reduced bacterial load upon challenge in the MV immunized group, and the RNA expression of several immune related genes altered, including mpeg1.1, tnfα, il1b, il10 and il6. MVs induced the secretion of IgM upon immunization, suggesting an immunogenic effect of the vesicles. Taken together, the data indicate a vaccine potential of MVs against SRS.

There is a growing interest in assessing human health effects of persistent organic pollutants (POPs), and several studies have reported in vitro or in vivo effects related to cancer. The main aim of this study was to assess the potential effect of perfluorinated compounds (PFCs) on breast cancer development in vitro, using the MCF-10A human mammary epithelial cell line. Both MCF-10A monolayer and three-dimensional cultures were used to study the effect of PFCs in a time-dose-dependent manner. Flow cytometry was used to assess the cell cycle distribution of monolayer cultures. The percentage of cells in Sub-G0/G1, G0/G1, S and G2/M were analyzed after 24, 48 and 72 hours in cells treated with 0, 100, 200, 300, 400 and 500 µM perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnA). In this study only high concentrations of PFOS, PFNA and PFDA affected the cells, demonstrated by an increased percentage of cells in Sub-G0/G1. To further investigate the effect of PFCs, laser scanning confocal microscopy was used to study acini polarization and lumen formation in MCF-10A three-dimensional cultures, treated with 0, 0.6, 6 and 60 µM of the same PFCs as the monolayer cultures. Alterations in polarization were determined at day 8 and 12, and lumen formation at day 3, 5, 7 and 10. MCF-10A cells organize into three-dimensional cultures, generating acini, when grown on a laminin-rich extracellular matrix. Acini formation begins with the clearance of the inner cells by apoptosis, to form lumen, followed by polarization of the outer cells. The in vitro observations showed that acini associated cell polarization and lumen clearance were compromised in three-dimensional cultures exposed to PFOS, PFNA, PFDA and PFUnA, even at the lowest exposure doses. In addition effects on lumen formation were observed due to PFOA exposure. Overall, this study demonstrated a difference in sensitivity between MCF-10A monolayer and three-dimensional cultures, and suggested a potential effect of PFCs on breast cancer development. Persistente organiske miljøgifter og deres effekt på human helse har de siste årene fått økt oppmerksomhet, og en rekke studier har rapportert in vitro eller in vivo eksponerings effekter, inkludert kreftutvikling. Hovedformålet ved denne studien var å evaluere den potensielle effekten av perfluorerte forbindelser (PFCs) med hensyn på brystkreft in vitro, ved bruk av MCF-10A humane brystepitelceller. Både MCF-10A monolag og tredimensjonale kulturer ble benyttet for å studere effekten av PFCs i en tid-dose-avhengig tilnærming. Flow cytometry ble benyttet for å evaluere cellesyklusdistribueringen i monolagkulturer. Andelen celler i SubG0/G1, G0/G1, S og G2/M ble analyserte etter henholdsvis 24, 48 og 72 timer av celler behandlet med 0, 100, 200, 300, 400 and 500 µM perfluoroktankarboksylsyre sulfonsyre (PFOS), perfluoroktylsyre (PFOA), perfluoronononansyre (PFNA), og perfluorodekansyre (PFDA) og Perfluoroundekansyre (PFUnA). Av de fem stoffene testet, påvirket PFOS, PFNA og PFDA cellene, ved å øke antall celler i Sub-G0/G1. For ytterligere å undersøke effekten av PFCs, ble det benyttet laser skanning konfokal mikroskopi for å studere polarisering og lumen dannelse i MCF-10A acini strukturer. De tredimensjonale kulturene ble behandlet med 0, 0,6, 6 og 60 µM av de samme stoffene brukt på monolagkulturer. Endringer i acini polarisering ble analysert ved dag 8 og 12, og lumen dannelse ved dag 3, 5, 7 og 10. MCF-10A celler danner tredimensjonale strukturer ved kontakt med laminin-rik ekstracellulær matrix, som gir opphav til acini strukturer. Acini dannelsen initieres ved apoptose av det indre laget med celler for dannelse av lumen, etterfulgt av polarisering av det ytre cellelaget. In vitro observasjonene indikerte komprimert polarisering og lumen dannelse i acini eksponert for PFOS, PFNA, PFDA og PFUnA, selv ved lave eksponerings konsentrasjoner. I tillegg ble det observert endringer i lumen dannelse ved PFOA eksponering. Resultatene presentert i denne studien viser med dette en forskjell i sensitivitet mellom MCF-10A monolag og tredimensjonale kulturer, samt en potensiell link mellom PFCs eksponering og økt risiko for brystkreft.