Interactions of Neisseria meningitidis with cells of the human meninges

The interaction of Neisseria meningitidis with the meninges that surround a nd protect the brain is a pivotal event in the progression of bacterial men ingitis. Two models of the human meninges were established in vitro, using (i) sections of fresh human brain and (ii) cultures of viable cells grown f rom human meningiomas. Neisseria meningitidis showed a specific predilectio n for binding to the leptomeninges and meningeal blood vessels in human bra in and not to the cerebral cortex. There was a close correlation between th e adherence of different Neisseria species to leptomeninges and cultured ce lls. The major ligand that mediated adherence was the pilus, and pilin vari ation modulated the interactions. The presence of Opa protein increased the association of Cap(+) meningococci that expressed low-adhesive pill, but d id not influence the association of high-adhesive pill. In contrast, Ope di d not influence the adherence of Cap(+) meningococci, whereas loss of capsu le was associated with a more intimate interaction between the bacteria and the meningioma cell that was not apparent with Cap(+) meningococci. There was no evidence of internalization of meningococci by meningioma cells in v itro, an observation that is consistent with the barrier properties of the leptomeninges to N. meningitidis observed in vivo.