High-Throughput LC–MS/MS Proteomic Analysis of a Mouse Model of Mesiotemporal Lobe Epilepsy Predicts Microglial Activation Underlying Disease Development

Uncovering the molecular
mechanisms of mesiotemporal lobe epilepsy
(MTLE) is critical to identify therapeutic targets. In this study,
we performed global protein expression analysis of a kainic acid (KA)
MTLE mouse model at various time-points (1, 3, and 30 days post-KA
injection -dpi), representing specific stages of the syndrome. High-resolution
liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS),
in combination with label-free protein quantification using three
processing approaches for quantification, was applied. Following comparison
of KA versus NaCl-injected mice, 22, 53, and 175 proteins were differentially
(statistically significant) expressed at 1, 3 and 30dpi, respectively,
according to all three quantification approaches. Selected findings
were confirmed by multiple reaction monitoring LC–MS/MS. As
a positive control, the astrocyte marker GFAP was found to be upregulated
(3dpi: 1.9 fold; 30dpi: 12.5 fold), also verified by IHC. The results
collectively suggest that impairment in synaptic transmission occurs
even right after initial status epilepticus (1dpi), with neurodegeneration
becoming more extensive during epileptogenesis (3dpi) and sustained
at the chronic phase (30dpi), where also extensive glial- and astrocyte-mediated
inflammation is evident. This molecular profile is in line with observed
phenotypic changes in human MTLE, providing the basis for future studies
on new molecular targets for the disease.