In patients with drug-resistant focal epilepsy requiring surgery, hippocampal sclerosis was the most common histopathological diagnosis among adults, and focal cortical dysplasia was the most common diagnosis among children. Tumors were the second most common lesion in both groups. (Funded by the European Union and others.).

Deposition of the beta-amyloid peptide (Abeta) in the brain occurs during normal ageing and is substantially accelerated in patients with Alzheimer's disease. Since Abeta is continuously produced in the brain, it has been suggested that a clearance mechanism should exist to prevent its accumulation and subsequent aggregation. Until now, little attention has been paid to the possible role of P-glycoprotein (P-gp), a member of the ATP binding cassette superfamily of transporter proteins, in the pathogenesis of Alzheimer's disease. A recent study demonstrated that Abeta40 and Abeta42 interact directly with P-gp. We therefore hypothesized that Abeta accumulation in the brain would correlate inversely with the degree of vascular P-gp expression. To study early pathogenetic factors that influence the deposition of Abeta, at routine autopsies, brain tissue samples were taken from 243 non-demented subjects who died between the ages of 50 and 91 years. Vascular P-gp expression and the number of Abeta40- and Abeta42-positive senile plaques were assessed immunohistochemically in the medial temporal lobe. In addition, the apolipoprotein E (apoE) genotypes, as well as multiple drug resistance gene 1 ( ) polymorphisms (exon 2, G-1A; exon 21, G2677T/A; exon 26, C3436T), were also determined for each case. P-gp expression was not correlated with genotypes, but we found a significant inverse correlation between P-gp expression and the deposition of both Abeta40 and Abeta42 in the medial temporal lobe. Our results provide the first evidence in human brain tissue that the accumulation of Abeta may be influenced by the expression of P-gp in blood vessels, and suggest that P-gp may influence the elimination of Abeta from brain.

Amyloid-beta (Abeta) is the major component of the insoluble amyloid plaques that accumulate intracerebrally in patients with Alzheimer's disease (AD). It has been suggested that MDR1-P-glycoprotein (ABCB1, P-gp) plays a substantial role in the elimination of Abeta from the brain. In the present study, MDR1-transfected LLC cells growing in a polarized cell layer were used to characterize the interaction of Abeta1-40/1-42 with P-gp. In this system, P-gp-mediated transport can be followed by the efflux of the fluorescent dye rhodamine-123, or of Abeta itself from the cells into the apical extracellular space. Abeta significantly decreased the apical efflux of rhodamine-123, and the transcellular transport of Abeta1-40 and Abeta1-42 into the apical chamber could be demonstrated using both ELISA and fluorescence (FITC)-labeled peptides. This transport was inhibited by a P-gp modulator. Furthermore, ATP-dependent, P-gp-mediated transport of the fluorescence-labeled peptides could be demonstrated in isolated, inside-out membrane vesicles. Our data support the concept that P-gp is important for the clearance of Abeta from brain, and thus may represent a target protein for the prevention and/or treatment of neurodegenerative disorders such as AD.

OATP2B1 is a high-affinity uptake transporter for atorvastatin and is expressed in the vascular endothelium of the human heart, suggesting its involvement in cardiac uptake of atorvastatin.

It has been shown in vitro that beta-amyloid (Abeta) is transported by P-glycoprotein (P-gp). Previously, we demonstrated that Abeta immunoreactivity is significantly elevated in brain tissue of individuals with low expression of P-gp in vascular endothelial cells. These findings led us to hypothesize that P-gp might be involved in the clearance of Abeta in normal aging and particularly in Alzheimer's disease (AD). As we were interested in the early pathogenesis of Abeta deposition, we studied the correlation between cerebral amyloid angiopathy (CAA) and P-gp expression in brain tissue samples from 243 non-demented elderly cases (aged 50 to 91 years). We found that endothelial P-gp and vascular Abeta were never colocalized, i.e., vessels with high P-gp expression showed no Abeta deposition in their walls, and vice versa. Abeta deposition occurred first in arterioles where P-gp expression was primarily low, and disappeared completely with the accumulation of Abeta. At this early stage, P-gp was upregulated in capillaries, suggesting a compensatory mechanism to increase Abeta clearance from the brain. Capillaries were usually affected only at later stages of CAA, at which point P-gp was lost even in these vessels. We hypothesize that Abeta clearance may be altered in individuals with diminished P-gp expression due, e.g., to genetic or environmental effects (such as drug administration). The impairment of Abeta clearance could lead to the accumulation and earlier deposition of Abeta, both in the walls of blood vessels and in the brain parenchyma, thus elevating the risk of CAA and AD.