Barrier To Electrical Storms

摘要

Epilepsy is characterized by repetitive seizures due to abnormal electrical activity in the brain. Immune cells promote development of this disorder by mediating the breakdown of the blood-brain barrier. It has long been thought that epilepsy is mainly caused by structural changes in the central nervous system, without much input from outside this system. The blood-brain barrier has, however, been a candidate for helping to protect the brain from seizures: it maintains ionic and metabolic homeostasis in the central nervous system, excluding serum and circulating cells while facilitating the passage of essential substances such as glucose. Indeed, several studies have shown that compromising this barrier aids the initiation and progression of epilepsy, even in the absence of structural damage to brain tissue. Two reports, including one by Kim et al. on page 191 of this issue, now take us a step further by documenting the involvement of inflammatory cells in the leakiness of the blood-brain barrier in mouse models of seizures and epilepsy. Infection of the mouse central nervous system with lymphocytic choriomeningitis virus (LCMV) results in the breakdown of the blood-brain barrier and fatal seizures. This condition had been believed to occur when T cells expressing the CD8 marker protein (CD8~+ T cells) recognized virus-infected cells, bound to them and killed them. Kim and colleagues tested this hypothesis by performing a detailed dynamic study in the LCMV-mouse model, visualizing fluorescently labelled CD8~+ T cells through the intact skull using two-photon microscopy.