APOE and susceptibility to pneumonia measurement: In our model, we have previously shown that inoculation of S. pneumoniae in ApoE−/− mice resulted in a significant proportion (48%) of these animals developing changes consistent with pneumonia on magnetic resonance imaging (MRI), and by limiting our analyses only to those inoculated mice that survive the S. pneumoniae challenge, our model more likely resembled the non-fatal forms of pneumonia in humans21.