Microglia and the immune response to a human temporal lobe seizure

Inflammatory processes and cells of the immune system including brain-resident microglia are activated in the epilepsies. We examined shape, transcriptomic profile and expression of microglial markers in tissue from the temporal lobe of epileptic patients. In the basal state, transcripts and pathways associated with the anti-inflammatory cytokine IL10, were up-regulated in the tissue from more sclerotic regions. We found that seizures also induce dynamic immune responses and change microglial phenotype. A pseudo-temporal ordering of the delay between the last seizure and tissue and analysis, based on immediate early gene expression, indicated an initial and local, innate immune response. At longer pseudo-time delays, infiltration of extra-cerebral cells, principally T-cells, contributed to the immune response. Ictal-like activity or ADP application in slices reproduced microglial activation including changes in motility and the liberation of inflammatory cytokines. Overall design: Comparison of 4 hippocampus regions from 13 human patients with MTLE (temporal lobe epilepsy with hippocampal sclerosis)