[P2-152] Hippocampal injury caused by lipoteichoic acid of Staphylococcus aureus in immature rat brains
Neurological sequelae of infants born as preterm remain as one major problem among many. Bacterial infection is known to be a risk factor of brain injury, and we investigated the effects of lipoteichoic acid (LTA), a cell-wall component of Staphylococcus aureus, which is the most common pathogen of Gram-positive bacterial infection in NICU, on immature brain. Cerebra of rats subjected to injection of LTA on day 3 were histologically examined on day 10. LTA caused neuronal injury, localized to hippocampus, and pyramidal neurons in CA1 and CA3 demonstrated pathological changes, such as marked shrinkage. Furthermore, up-regulation of immunoreactivity to cleaved caspase-3 in pyramidal neurons was observed in CA3 in LTA-injected rats, indicating the involvement of apoptotic mechanism. Toll-like receptor 2 (TLR2), which detects LTA and provokes inflammatory responses, is immunohistochemically expressed in rat cerebra on day 3, including hippocampal pyramidal neurons. Therefore, LTA may induce hippocampal injury possibly through TLR2 activation in S. aureus infection, leading to neuro-cognitive deficits of infants born as preterm.