Cellular expression of low-density lipoprotein receptor-related protein 1 and amyloid beta deposition in human and rat epileptogenic brain.

Decreased capillary expression of low-density lipoprotein receptor-related protein 1 (LRP1) has been linked to increased brain amyloid beta (Aβ) accumulation in Alzheimer's disease (AD). Aβ accumulation has also been observed in (a subset of) temporal lobe epilepsy (TLE) patients, suggesting a potential link between epilepsy and AD. This study examines cellular LRP1 expression in human and rat epileptogenic brain tissue to explore LRP1's role in epilepsy. LRP1 expression and localization were analyzed in hippocampal sections from patients with status epilepticus (SE, n = 12), TLE (n = 12), autopsy controls (n = 20), and AD (n = 10) using immunohistochemistry. Soluble Aβ levels and deposits were compared across TLE, AD, and control tissues. LRP1 expression was also studied in an electrical post-SE rat model of TLE. Decreased capillary LRP1 expression was found in both human and rat brain tissue (SE and TLE). Higher LRP1 expression was detected in CA1 neurons (only in human TLE) and glial cells (SE and TLE). Aβ deposits were observed in only one out of 12 TLE patients, and soluble Aβ levels were not significantly elevated. In contrast, AD patients showed decreased capillary LRP1 expression accompanied by Aβ plaques and increased soluble Aβ40/42 levels. The significant reduction in LRP1 expression in brain capillaries in both adult human and rat TLE was not clearly associated with notable Aβ accumulation implying that alternative amyloid clearance mechanisms beyond LRP1 in blood vessels might be at play. It also supports previous findings indicating that Aβ pathology may be less prominent in adult TLE than some studies suggest.