Abstract
Pentamidine is an effective trypanocidal drug used against stage 1 Human African Trypanosomiasis (HAT). At the blood-brain barrier (BBB), it accumulates inside the endothelial cells but has limited entry into the brain. This study examined transporters involved in pentamidine transport at the human and mouse BBB using hCMEC/D3 and bEnd.3 cell lines, respectively. Results revealed that both cell lines expressed the organic cation transporters (OCT1, OCT2 and OCT3), however, P-gp was only expressed in hCMEC/D3 cells. Polarised expression of OCT1 was also observed. Functional assays found that ATP depletion significantly increased [3H]pentamidine accumulation in hCMEC/D3 cells (***p<0.001) but not in bEnd.3 cells. Incubation with unlabelled pentamidine significantly decreased accumulation in hCMEC/D3 and bEnd.3 cells after 120 minutes (***p<0.001). Treating both cell lines with haloperidol and amantadine also decreased [3H]pentamidine accumulation significantly (***p<0.001 and **p<0.01 respectively). However, prazosin treatment decreased [3H]pentamidine accumulation only in hCMEC/D3 cells (*p<0.05), and not bEnd.3 cells. Furthermore, the presence of OCTN, MATE, PMAT, ENT or CNT inhibitors/substrates had no significant effect on the accumulation of [3H]pentamidine in both cell lines. From the data, we conclude that pentamidine interacts with multiple transporters, is taken into brain endothelial cells by OCT1 transporter and is extruded into the blood by ATP-dependent mechanisms. These interactions along with the predominant presence of OCT1 in the luminal membrane of the BBB contribute to the limited entry of pentamidine into the brain. This information is of key importance to the development of pentamidine based combination therapies which could be used to treat CNS stage HAT by improving CNS delivery, efficacy against trypanosomes and safety profile of pentamidine.
Highlights
Pentamidine is an aromatic diamidine that is used clinically to treat the haemolymphatic stage of Human African Trypanosomiasis (HAT)
The MRC DPFS award is jointly funded by the UK Medical Research Council (MRC) and the UK Department for International Development (DFID) under the MRC/DFID Concordat agreement and is part of the EDCTP2 programme supported by the European Union
The results show that compared to control conditions, accumulation of [3H]pentamidine in both hCMEC/D3 and bEnd.3 cells decreased significantly (Fig 1) (ÃÃÃp
Summary
Pentamidine is an aromatic diamidine that is used clinically to treat the haemolymphatic stage of Human African Trypanosomiasis (HAT). It is used to treat American cutaneous leishmaniasis and as a prophylactic for Pneumocystis jirovecii pneumonia [1]. N1eFCQplO6rhh8Ab5fNSuC5QjMMrgbdkTm0% 3D&reserved=0 PhD studentship MR/K500811/1), a MRC DPFS award (MR/K015451/1) and a multiuser equipment grant from The Wellcome Trust The MRC DPFS award is jointly funded by the UK Medical Research Council (MRC) and the UK Department for International Development (DFID) under the MRC/DFID Concordat agreement and is part of the EDCTP2 programme supported by the European Union. The MRC DPFS grant was awarded to Dr S.A. Thomas (PI), Dr C.A. Dreiss, Dr C. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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