Grant: Master's Award: Canada Graduate Scholarships

Bacterial infection and diseases remain one of the largest health crises around the world. When bacteria infect humans, they stimulate various immune cells that recognize and eliminate the infection. Macrophages, a type of immune cell, hunt, identify and destroy bacteria. Macrophages recognize molecules present on the bacterial cell surface called pathogen associated molecular patterns (PAMPs), which act as identity tags. Once macrophages have identified these tags they can either release chemical toxins or engulf the bacteria and degrade them within the cell. This engulfing process, called phagocytosis results in the cellular internalization of bacteria into a phagosome. Phagosomes then fuse with lysosomes, to help degrade the bacteria. Lysosomes are stomach like in that they are highly acidic, degradative and eliminate infections. Interestingly, when macrophages are exposed to the bacterial PAMP, lipopolysaccharide (LPS), their lysosomes change from small spherical bodies to large tubular networks. The function and biogenesis of tubular lysosomes is not understood, though we speculate that it may aid in antigen degradation. To help address this, we are interested in comparing the differences in the biochemical, biophysical and functional properties such as acidic content, degradative capacity and lysosomal volume, between punctate and tubular lysosomes. It is hypothesized that significant differences in lysosome properties will be identified and help guide future research towards understanding the functional relevance of this dramatic change in lysosomal morphology upon LPS exposure. Overall, this project will help us to understand the mechanisms that regulate the immune system's response for fighting an infection.