TSPO PET upregulation predicts epileptic phenotype at disease onset independently from chronic TSPO expression in a rat model of temporal lobe epilepsy.
Level 5 - mechanism / opinion, no new human data
Animal model study without human participants
PubMed 34090124 · doi:10.1016/j.nicl.2021.102701
What was done
Controls (n = 14) and kainic acid-induced status epilepticus (KASE) rats (n = 41) underwent non-invasive [18F]PBR111 PET imaging to quantify TSPO neuroinflammation at disease onset (2 weeks post-status epilepticus). Rats were monitored with video-electroencephalography (vEEG) up to chronic disease (12 weeks post-status epilepticus), after which post-mortem evaluations measured chronic TSPO binding ([3H]PK11195), synaptic density ([3H]UCB-J), neuronal loss (NeuN), and neurodegeneration (Fluoro-Jade C).
What was found
Multivariate analysis of onset TSPO PET stratified KASE rats into three groups with significantly different spontaneous recurrent seizure (SRS) burdens (rare, sporadic, and frequent; p = 0.003). Baseline TSPO levels differed significantly across these three groups (p < 0.0001), with the frequent SRS group exhibiting only a limited focal TSPO increase at onset. In contrast, chronic-stage TSPO was highest in the frequent SRS group and correlated with seizure burden (r = 0.826, p < 0.0001). Early and chronic TSPO levels did not correlate (r = -0.05). Significant differences in neuronal loss, synaptic density, and neurodegeneration were present versus controls (p < 0.01) and among the three KASE categories in the hippocampus (p < 0.05).
Why it matters
The study suggests neuroinflammation involves two distinct dynamic phases in epileptogenesis, where early TSPO levels provide prognostic value for seizure phenotype while chronic TSPO reflects ongoing seizure frequency.
Limits
The study is restricted to a chemically induced rodent model, which may not fully replicate human epileptogenesis. The sample size after dividing the 41 model rats into three subgroups is small, and specific absolute PET quantification values and confidence intervals were not provided in the abstract.
Cited by
- partial PET imaging of neuroinflammation in the brain can predict the occurrence of epileptic seizures.