SPP1 and pneumonia: Besides these studies on increased levels of OPN in the plasma of patients with interstitial (Kadota et al., 2005) and community-acquired pneumonia (Chang et al., 2016), and in the plasma and lung of mice infected with Streptococcus pneumonia (van der Windt et al., 2011), the cardiomyocyte expression of OPN and its role in pneumonia-mediated cardiac dysfunction have not been investigated.