Abstract
Background: The quantification of tissue expression of drug transporters is important in pharmacokinetic studies to understand the disposition of drugs and their metabolites and predict drug clearance and drug-drug interactions. Changes in transporter expression are thought to be implicated in various conditions, including Alzheimer’s disease (AD). Recent advances in quantitative proteomics can enable measurement of transporters in the blood-brain barrier (BBB), and therefore can be used to develop pharmacokinetic models for psychoactive drugs. This study aimed to implement global and targeted proteomic approaches to quantify the main drug transporters in human brain microvessels.
Methods: Brain microvessels were isolated from brain tissue (2.5-3.0 grams) of 12 healthy, 8 Alzheimer’s and 2 dementia patients. A QconCAT with selected peptides from target transporters was used as an internal standard for quantification using LC-MS/MS. Spectroscopic methods were used to determine the individual protein content of microvessel fractions per gram brain.
Results: Brain microvessel protein content was determined in healthy and disease samples as 0.27 and 0.36 mg/gram brain, respectively. The purity of isolated microvessels was demonstrated using brain endothelial markers. Targeted and label-free quantification demonstrated similarities and differences in transporter expression levels between healthy and AD brains. For example, a similar level of ABCB1/P-gp/MDR1 was shown in AD (6.26 pmol/mg) and healthy (6.54 pmol/mg) donors. By contrast, ABCG2/BCRP was below the limit of quantification in AD samples compared to expression levels at 8.27pmol/mg in healthy samples. Similarly, ABCC2/MRP2 was not detected in AD samples and measured at low levels in healthy donors (0.35 pmol/mg).
Conclusions: Preliminary data demonstrated differences in expression levels of transporters in the BBB of healthy and AD patients. These data can be used as scaling factors for brain in vitro in vivo extrapolation (IVIVE) and pharmacokinetic modelling in AD research.
Keywords: Drug transporters, Protein quantification, QconCAT, Alzheimer’s disease (AD)
Methods: Brain microvessels were isolated from brain tissue (2.5-3.0 grams) of 12 healthy, 8 Alzheimer’s and 2 dementia patients. A QconCAT with selected peptides from target transporters was used as an internal standard for quantification using LC-MS/MS. Spectroscopic methods were used to determine the individual protein content of microvessel fractions per gram brain.
Results: Brain microvessel protein content was determined in healthy and disease samples as 0.27 and 0.36 mg/gram brain, respectively. The purity of isolated microvessels was demonstrated using brain endothelial markers. Targeted and label-free quantification demonstrated similarities and differences in transporter expression levels between healthy and AD brains. For example, a similar level of ABCB1/P-gp/MDR1 was shown in AD (6.26 pmol/mg) and healthy (6.54 pmol/mg) donors. By contrast, ABCG2/BCRP was below the limit of quantification in AD samples compared to expression levels at 8.27pmol/mg in healthy samples. Similarly, ABCC2/MRP2 was not detected in AD samples and measured at low levels in healthy donors (0.35 pmol/mg).
Conclusions: Preliminary data demonstrated differences in expression levels of transporters in the BBB of healthy and AD patients. These data can be used as scaling factors for brain in vitro in vivo extrapolation (IVIVE) and pharmacokinetic modelling in AD research.
Keywords: Drug transporters, Protein quantification, QconCAT, Alzheimer’s disease (AD)
Original language | English |
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Title of host publication | HUPO2017 |
Publication status | Published - 19 Sept 2017 |
Event | 16th Human Proteome Organization World Congress - Dublin - Convention Centre (CCD), Dublin, Ireland Duration: 17 Sept 2017 → 20 Sept 2017 http://hupo2017.ie/ |
Conference
Conference | 16th Human Proteome Organization World Congress - Dublin |
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Country/Territory | Ireland |
City | Dublin |
Period | 17/09/17 → 20/09/17 |
Internet address |