The gut is a major site of pathogen entry such as food-borne pathogens yet is also home to a diverse commensal microbial community-the microbiome. The immune response in the gut is complex, as it has to both be tolerant to the commensal microbiome and have the appropriate response to gut pathogens. Dendritic cells (DCs) are key cells in shaping the immune response through linking innate and adaptive immunity and their ability to migrate to sites of infection and sites of T cells priming is fundamental to their role. The immune response may be dependent on the efficiency of DC migration and subsequent ability to trigger T cell activation and thus be linked to resistance versus susceptibility to disease. Previous data from our group showed that the speed of the DC migratory response to infection is associated with resistance versus susceptibility to infection. Studying the migration phenotype of DCs undertakes in response to gut infections and their interaction with their surrounding tissue environment is the main focus of my study. DC subsets express cellular adhesion molecules known as integrins but it is still debatable whether integrins have a role in DC migration in steady state and during infection. I hypothesised that DC subsets within the intestine respond and migrate differently to pathogens and this influences the subsequent immune response. In vitro models were developed using bone marrow DCs (BMDC) isolated from C57BL/6 mice in which the CD11c cells were tagged with a yellow fluorescence reporter gene (CD11cYFP) and stimulated with parasite antigens in the presence or absence of integrin ligands. Data was compared with ex vivo analysis from infections. Our in vitro data showed that BMDCs stimulated with antigens from the gut parasites Trichuris muris, Trichinella spiralis or Toxoplasma gondii antigens promoted diverse migration speeds and displacement lengths. I used Itgb2mut mice to assess the role of β2 integrin in DC migration during gut infection with T. muris. This study revealed the importance of β2 integrin in DC recruitment to the site of infection (colon) and to the MLNs to activate T cells during inflammation. Pilot studies were also performed to develop an in vitro co-culture model of intestinal organoids, T. gondii and DCs, which may be used in future studies to assess DC/epithelial interactions in the context of health and infection. Overall my study suggested that integrins are important for DC migration but that DCs were not critical for resistance to infection with T. muris. Furthermore, I showed that parasite products can directly promote DC migration
Dendritic cell migration in the intestine in response to infection
Altorki, T. (Author). 1 Aug 2017
Student thesis: Phd