An Atlas of the Quantitative Protein Expression of Anti-Epileptic-Drug Transporters, Metabolizing Enzymes and Tight Junctions at the Blood–Brain Barrier in Epileptic Patients

Abstract

The purpose of the present study was to quantitatively elucidate the levels of protein expression of anti-epileptic-drug (AED) transporters, metabolizing enzymes and tight junction molecules at the blood–brain barrier (BBB) in the focal site of epilepsy patients using accurate SWATH (sequential window acquisition of all theoretical fragment ion spectra) proteomics. Brain capillaries were isolated from focal sites in six epilepsy patients and five normal brains; tryptic digests were produced and subjected to SWATH analysis. MDR1 and BCRP were significantly downregulated in the epilepsy group compared to the normal group. Out of 16 AED-metabolizing enzymes detected, the protein expression levels of GSTP1, GSTO1, CYP2E1, ALDH1A1, ALDH6A1, ALDH7A1, ALDH9A1 and ADH5 were significantly 2.13-, 6.23-, 2.16-, 2.80-, 1.73-, 1.67-, 2.47- and 2.23-fold greater in the brain capillaries of epileptic patients than those of normal brains, respectively. The protein expression levels of Claudin-5, ZO-1, Catenin alpha-1, beta-1 and delta-1 were significantly lower, 1.97-, 2.51-, 2.44-, 1.90- and 1.63-fold, in the brain capillaries of epileptic patients compared to those of normal brains, respectively. Consistent with these observations, leakage of blood proteins was also observed. These results provide for a better understanding of the therapeutic effect of AEDs and molecular mechanisms of AED resistance in epileptic patients.

Glucocorticoid Receptor β Isoform Predominates in the Human Dysplastic Brain Region and Is Modulated by Age, Sex, and Antiseizure Medication

“…In a study done with bone marrow-derived macrophages, LPS-induced resistance to DEX treatment was attributed to a 7-fold increase in GRβ mRNA levels in these cells [34], which could explain the resistance to DEX-mediated claudin-5 increase in HBMEC+HA-GRβ or EPI-ECs in our study. Interestingly, a recent study has also found that claudin-5 expression was significantly decreased 1.97-fold in epileptic brain microvessels compared to controls, but occludin expression was not significantly different between the two groups [35]. This supporting evidence further confirms that the decrease in tight junction proteins in the epileptic brain region may not afflict all types of tight junction proteins, and we describe here for the first time that GRβ may play a role in that phenomenon.…”

Protein Expression of Amino Acid Transporters Is Altered in Isolated Cerebral Microvessels of 5xFAD Mouse Model of Alzheimer’s Disease

“…Here, we applied previously developed sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based quantitative targeted absolute proteomics (QTAP) methods [28,29]. The LC-MS/MS-based QTAP approach enables a sensitive and robust quantitative analysis of low abundant target proteins with multiple advantages over the antibody-based methods such as western blotting [30], and has been extensively applied for protein expression quantification of transporters and other proteins in the NVU in health and diseases [17,28,29,[31][32][33][34][35]. Moreover, we compared the alterations in transporter protein expression in the isolated brain microvessels and brain prefrontal cortices of 5xFAD mice to previously published data in AD patients and other animal models in order to assess the relevance of the animal models to mimic AD-related changes in transporter protein expression in the NVU in humans.…”

In silico screening for clinical efficacy of antiseizure medications: Not all central nervous system drugs are alike

“…However, some other brain disorders are also characterized by P‐gp upregulation 19,20 . Moreover, recent proteomic analyses suggest the P‐gp is globally underexpressed and not overexpressed in the epileptogenic human brain 21,22 . Likewise, key tight junction proteins are downregulated in the epileptogenic brain, 22,23 supporting looser rather than tighter barrier than in the healthy brain.…”

“… 19 , 20 Moreover, recent proteomic analyses suggest the P‐gp is globally underexpressed and not overexpressed in the epileptogenic human brain. 21 , 22 Likewise, key tight junction proteins are downregulated in the epileptogenic brain, 22 , 23 supporting looser rather than tighter barrier than in the healthy brain. Alternatively, seizures might theoretically alter the porosity of endothelial cell membranes, thereby slowing down or preventing drug “jumping” through transitory holes in the membrane.…”