Macrophages represent the first line of defence against pathogens and play important roles in major infectious diseases. Because of the availability of inbred strains and gene deficient animals, macrophage-pathogen interactions are studied largely using mice. Macrophages can be best investigated using either organ-derived or ex vivo produced primary macrophages (BMDMs), but the availability of such cells is limited. Lung alveolar macrophages (AMs) play central roles in defence against respiratory bacterial pathogens, however, bacteria may overcome macrophage killing mechanisms. Bacteria unavailable to drugs inside macrophages may represent an important problem in the treatment of bacterial infections of the airways.
We described a novel, self-renewing, non-transformed, primary murine model of AMs, providing unrestricted amounts of primary macrophages. Using this system we have demonstrated the very high sensitivity of MPI cells and AMs to respiratory pathogens and have shown the existence of unique innate pathogen sensing pathways in these cells. The innate recognition of respiratory bacteria by AMs involves various sensors, but the understanding of their contribution to pathogenesis mechanisms is hampered by the restricted availability of AMs.
Here we will transfer the MPI cell technology to the King's College London and the Institut Pasteur, Korea to study bacterial pathogenesis in lung macrophages. We will establish new MPI cell lines from mice lacking various bacterial pathogen recognition sensors such as scavenger and C-type lectin receptors, Toll-like Receptors and cytoplasmic sensors. To make the cells accessible to other researchers we will make a repository of the new cell lines and/or distribute them through commercial vendors to the wider community. We have ongoing studies with these bacteria and will use the new cell lines to obtain mechanistic data regarding the activation of innate pathways to the sensing of respiratory bacterial infections.