Roles of the Choroid Plexus in CNS Infections

The choroid plexus (CP) is a highly vascularized endothelial-epithelial convolute located in the ventricular system of the brain. The CP is also the localization of the blood-cerebrospinal fluid barrier (BCSFB), which is formed by the CP epithelium. During infectious diseases of the central nervous system (CNS) the CP can play multiple roles, which will be covered by this review. To cause infection of the CNS pathogens need to cross into the brain, and the CP can present the site of entry across the BCSFB. For invading the CNS pathogens have evolved several mechanisms that can require the help of host immune cells. Infections with pathogens often also cause cell death in the CP, which can be responsible for impairment of barrier function. The CP reacts to the intruders by staging an inflammatory response involving the production of cytokines and chemokines and can function as an entry gate for host immune cells. Following entry of pathogens and host immune cells into the brain both players can cause severe damage leading to neurological sequelae. Additionally, impairment of important CP functions might be involved in further complications like hydrocephalus.