SPP1 and infection: Paliwal et al. (2012) reported higher OPN expression in macrophages of aged mice with skeletal muscle injury. Conversely, Schultz et al. (2002, 2004) reported exaggerated inflammatory responses in term and preterm infants compared to adults with attenuation of the pro-inflammatory reaction during infection that can lead to severe organ dysfunction in infants. Developing neonatal cardiomyocyte also differ from adults and there may be different responses to sepsis and inflammation (Luce et al., 2007).