Hippocampal dentate granule cells in temporal lobe epilepsy: A morphometry and transcriptomic study

Area of Science:

• Neuroscience
• Epileptology
• Molecular Biology

Background:

• The dentate gyrus (DG) is crucial for hippocampal function, acting as a gatekeeper to cornu ammonis (CA) sectors.
• Pathologies in the DG are less frequently documented in mesial temporal lobe epilepsy (mTLE) diagnoses compared to CA sectors.

Purpose of the Study:

• To investigate the role and characteristics of the DG in mTLE.
• To differentiate between hippocampal sclerosis (HS) and no-HS mTLE by analyzing DG morphometry and gene expression.
• To explore the prognostic value of DG morphometry for post-operative outcomes.

Main Methods:

• Analysis of morphometric parameters (cell spacing, nucleus size, circularity) in the DG.
• Gene expression profiling of DG tissue from mTLE patients (HS and no-HS) and controls.
• Comparison of DG characteristics across epilepsy and control cohorts.

Main Results:

• Distinct morphometric and RNA expression profiles were observed between HS and no-HS groups.
• Dentate granule cells were more dispersed in HS patients, with elevated expression of complement system, apoptosis, and extracellular matrix remodeling RNAs.
• A decrease in neurogenesis-related RNA was noted in HS DG.
• DG morphometry, specifically increased cell spacing, correlated with seizure freedom post-surgery, irrespective of pathology.

Conclusions:

• The study highlights significant differences in DG pathology between HS and no-HS mTLE, suggesting distinct underlying mechanisms.
• Dentate gyrus morphometry demonstrates potential as a prognostic indicator for surgical outcomes in mTLE.
• These findings support the concept of HS and no-HS mTLE as separate entities requiring tailored treatment approaches.