The effect of the pneumococcal toxin, pneumolysin on brain ependymal cilia

Densely ciliated ependymal cells cover the ventricular surface of the brain and cerebral aqueducts separating cerebrospinal fluid, which is infected i n meningitis, from neuronal tissue. We have established an ex vivo model th at allows measurement of ependymal ciliary beat frequency, using high-speed video analysis, during incubation with bacterial toxins. Ciliated ependyma , from Wistar rats, was exposed to the pneumococcal toxin, pneumolysin, and a mutant form with markedly reduced cytotoxic activity (similar to 0.1%). Wild-type pneumolysin (1500 HU/ml and 150 HU/ml: 10 and 1 mu g/ml) caused r apid ciliary stasis (30-150 s), sloughing of cilia and cytoplasmic extrusio n. Ciliary slowing before stasis was seen at 15 HU/ml (0.1 mu g/ml); howeve r, no effect on ciliary beat frequency was seen at lower concentrations (1. 5 HU/ml and 0.15 HU/ml: 0.01 and 0.001 mu g/ml). Mutant pneumolysin, 99.9% deficient in haemolytic activity, caused rapid ciliary stasis at 10 mu g/ml but no effect was seen at lower concentrations (1-0.1 mu g/ml). Pneumolysi n, at levels which may be produced during severe pneumococcal meningitis, m ay cause rapid ependymal ciliary stasis. (C) 1999 Academic Press.