PECAM1 and meningitis: Lethal meningitis caused by S. pneumoniae requires the penetration of the blood-brain-barrier (BBB) by the bacteria (Iovino et al., 2016b): an interaction of RrgA with polymeric immunoglobulin receptor (pIgR) and platelet endothelial cell adhesion molecule 1 (PECAM-1), two BBB endothelial receptors, was found to promote the entry of bacteria into the brain and meningitis development (Iovino et al., 2017).