Protein S-100B: A serum marker for ischemic and infectious injury of cerebral tissue

The S-100B protein is released by injured astrocytes. After passage through a disintegrated blood-brain barrier (BBB) the molecule can be detected in the peripheral circulation. We investigated the association between the ext ent of brain injury and S-100B concentration in serum in cerebral injury ca used by cerebral ischemia and cerebral fungal infection. Study I: The S-100B serum concentration was serially determined in 24 patie nts with ischemic stroke at 4, 8, 10, 24, 72 hours after the onset of sympt oms. We observed that patients with brain lesions larger than 5 cm(3) exhib ited significantly increased serum levels of S-100B at 10, 24 and 72 hours compared to those with lesion volumes below 5 cm(3). Furthermore, an associ ation between S-100B serum concentration and neurological outcome was obser ved. Study II: in a mouse model of systemic fungal infection with Candida albica ns we observed that serum levels of S-100B increased at day 1 after intrave nous infection. At this time we could histologically demonstrate brain tiss ue injury by invading hyphae which had crossed the BBB. Furthermore, reacti ve astrogliosis was demonstrated by immunohistochemistry. On day 7 we found a significant decrease of S-100B serum level compared to day 1 and 4. This was associated with a demarcation of the fungi with leukocytes in brain ti ssue at this late phase of infection. No further invasion through the BBB w as seen on day 7. In conclusion, serum levels of S-100B reflect the time course of tissue inj ury in cerebral ischemia and cerebral infection to a similar extent. Thus, S-100B may be a useful marker to assess cerebral tissue injury.