Microfluidic chip-enabled proteome profiling of bacterial infection of macrophages reveals new pathogenic regulators of immune evasion.

Microfluidic chip enabled cell sorting of non-phagocytosed K. pneumoniae cells from BALB/c macrophages during co-culture. These cell populations were analyzed to determine differences in phagocytosed K. pneumoniae versus non-phagocytosed at the protein level. This resulted in the identification of several iron-associated proteins associated with K. pneumoniae that evaded phagocytosis. Evidence in the literature indicated that secreted products from macrophages (i.e., cytokines) significantly increases expression of iron acquisition genes in bacteria, prompting our investigation (and the contents of our submission) into the changes in K. pneumoniae at the proteome-level when exposed to secretion products of macrophages exposed to pathogens (i.e., K. pneumoniae) versus unexposed, with specific emphasis on iron-associated proteins. It was confirmed that pathogen-exposed macrophage supernatant (i.e., activated macrophages induced higher production of iron-associated proteins in exposed K. pneumoniae compared to non-activated macrophages.