Biopharmacy (Meyer zu Schwabedissen)Head of Research Unit Prof. Dr.Henriette Meyer zu SchwabedissenOverviewMembersPublicationsProjects & CollaborationsProjects & Collaborations OverviewMembersPublicationsProjects & Collaborations Projects & Collaborations 8 foundShow per page10 10 20 50 Specificity, selectivity and pharmacokinetics of compstatin: a comprehensive multidisciplinary analysis Research Project | 6 Project MembersThe complement system plays a major role in innate immunity as it confers immune surveillance and first-line defense against non- or altered-self entities such as microbes or apoptotic cells. Yet, misguided complement activation may trigger or contribute to severe clinical conditions or complications, including autoimmune, hemolytic, inflammatory and age-related disorders and transplant rejection (PMID) [1]. Owing to its cascade organization, involving ~50 plasma proteins, receptors and enzymes, complement provides multiple points for novel pharmacological intervention [2]. However, few complement-targeted drugs have reached the clinic, and the available options primarily target peripheral steps in cascade initiation or effector generation. For many acute-phase or multifactorial complement disorders, blocking the activation of the central complement component C3 is considered important [3]. Derivatives of compstatin, a peptidic inhibitor of C3 activation [4], are the most advanced compounds in this class, with two candidate drugs being evaluated in clinical trials. However, its narrow species-specificity for primate C3 currently restricts a broader exploration of potential benefits of C3 inhibition in various established animal models of complement disorders. Furthermore, despite considerable progress in structure optimization, some pharmacokinetic and physicochemical properties of the compstatin class remain to be improved to fully unleash its unique therapeutic potential. The main objective of this project is to understand target binding and complement inhibition by compstatin in the human system at the atomic level and identify key determinants of its narrow species specificity. We will utilize this knowledge for designing compstatin analogs that recognize non-primate C3 and, for example, inhibit mouse, rat or pig complement. Simultaneously, we will assess compstatin's target selectivity for C3 over the orthologous C4 and C5 proteins and explore options for achieving C4-, C5- or pan-specific inhibitors for research or clinical applications. Finally, we will analyze and optimize the pharmacokinetic properties of compstatin with special emphasis on solubility and bioavailability. The proposed rationalization and optimization efforts will be driven by well-established in silico simulation techniques such as molecular dynamics simulations, free energy methods, homology modeling, and post-MD analyses, supported by novel approaches based on deep learning (Prof. Markus Lill, Computational Pharmacy). Thanks to project collaborations with strong experimental groups, in silico findings will be experimentally verified by employing peptide synthesis and characterization, chemical modification and labeling, and target binding and functional assays in vitro (Prof. Daniel Ricklin, Molecular Pharmacy) as well as pre-clinical assessments of cellular permeability in vitro and in vivo (Prof. Henriette Meyer zu Schwabedissen, Biopharmacy; all at University of Basel). Our studies are expected to extend preclinical evaluation options of compstatin-based drugs in animal models and enhance their pharmacokinetic profile, thereby facilitating clinical development of this important inhibitor class. Selectivity studies with C4/C5 may provide insight into complement activation and potentially reveal novel inhibitors. Finally, atomic level insight into the structure-activity/property relationships of cyclic peptides may be used for the design of this compound type in general. [1] Ricklin, D.; Reis, E. S.; Lambris, J. D. Complement in Disease: A Defence System Turning Offensive. Nat. Rev. Nephrol. 2016, 12 (7), 383-401. https://doi.org/10.1038/nrneph.2016.70. [2] Mastellos, D.C., Ricklin, D. & Lambris, J.D. Clinical promise of next-generation complement therapeutics. Nat Rev Drug Discov 18, 707-729 (2019). https://doi.org/10.1038/s41573-019-0031-6 [3] Mastellos, D. C.; Reis, E. S.; Ricklin, D.; Smith, R. J.; Lambris, J. D. Complement C3-Targeted Therapy: Replacing Long-Held Assertions with Evidence-Based Discovery. Trends Immunol. 2017, 38 (6), 383-394. https://doi.org/10.1016/j.it.2017.03.003. [4] Mastellos, D. C.; Yancopoulou, D.; Kokkinos, P.; Huber-Lang, M.; Hajishengallis, G.; Biglarnia, A. R.; Lupu, F.; Nilsson, B.; Risitano, A. M.; Ricklin, D.; Lambris, J. D. Compstatin: A C3-Targeted Complement Inhibitor Reaching Its Prime for Bedside Intervention. Eur. J. Clin. Invest. 2015, 45 (4), 423-440. https://doi.org/10.1111/eci.12419. Investigations on the impact of herbal extracts on intestinal handling of histamine Research Project | 3 Project MembersHistamine intolerance (HIT) is a common diagnosis with an estimated prevalence of 1% in the Western population. Patients suffering from HIT exposed to histamine present with various symptoms such as rhinal congestion, headache, tachycardia, diarrhea, urticaria, and eventually bronchoconstriction. Food-derived histamine is modulated by different mechanisms in the intestine. Two intestinal enzymes, diamine oxidase (DAO) and histamine-N-methyltransferase (HNMT), are reported to metabolize histamine. Moreover, transport proteins, such as Organic Cation Transporter 3 (OCT3) or Plasma Membrane Monoamine Transporters (PMAT), are believed to contribute to the transmembrane transport and thus the overall handling of histamine. Using an immortalized cell line originating from colon adenocarcinoma, Caco-2, we aim to elucidate the influence of herbal remedies used in clinics for their influence on the intestinal handling of histamine. In pre-experiments we successfully validated the expression of DAO and HNMT in Caco-2 cells. In a dose-finding experiment, we will first test a dilution series of herbal extracts in cell viability assays in order to exclude a negative effect on Caco-2 cell viability. Next we will investigate the effect of different concentrations of herbal extracts on DAO and HNMT mRNA and protein expression by real-time qPCR and Western blot analysis, respectively. Previously, it has been reported that Caco-2 cells exposed to heparin showed a significant increase in DAO release and DAO enzymatic activity. Accordingly, we will examine the effect of herbal extract on DAO content and DAO activity in the enriched secretome of Caco-2 cells applying Western blot analysis and a fluorometric DAO enzyme activity assay, respectively. Since herbal extract may potentially interact with the transcellular transport of food-derived histamine in the intestine, we will apply Caco-2 transwell transport studies to assess the influence on the uptake of radioactive [3H]-histamine as a tracer. Adding herbal extracts to the apical side of the transwell (representing the luminal side of the intestine) we will determine the apical-to-basal as well as the basal-to-apical transfer of histamine. Concluding we will perform transport interaction experiments testing for the impact of histamine handling by OCT3 or PMAT in presence or absence of herbal extracts. To investigate the role of OCT3 we will apply a MDCKII cell line stably expressing OCT3 (MDCKII-OCT3) and readily available in our laboratory. PMAT will be cloned from human brain cDNA. We will then use the vaccinia virus-assisted expression system to transiently overexpress PMAT in HeLa cells. Optimising paediatric dosing regimens based on a clinical data warehouse SwissPKcdw Research Project | 4 Project MembersThe project will build the SwissPharmacoKinetics clinical data warehouse SwissPK cdw , with encoded clinical, pharmacokinetic, physiological and genetic data from Swiss Children's Hospitals (real-world data). Within the project the collaborating groups will focus on the patients with highest need for optimised dosage regimens, namely the paediatric patients, and will include a pre-defined list of 1-3 drugs. The long-term goal beyond the funding period is to establish a dynamic, steadily growing CDW for any drug and any patient cohort. It is aim to significantly extend based on analytical evidence the current expert-opinio-only recommendations for drug dosage in paediatrics and to identify covariates which best predict the pharmacokinetics in children, including physiological factors, genetic polymorphisms in ADMET-relevant genes, disease-related factors and co-medication. Studies on the role of OATP1A2 and OATP2B1 in dopamine-agonist and -antagonist transport across the blood-brain barrier Research Project | 2 Project MembersIn order to enter the brain a compound has to cross the blood brain barrier (BBB), which efficiently protects the central nervous system from xenobiotic exposure. However, the protection is substrate specific as there are some compounds, which exert their pharmacological effect in the brain and are certainly able to cross the membrane, while others do not even if they are structurally related. It is widely known that membrane proteins are involved in cellular efflux and uptake, whereby influencing transcellular transport. The family of Organic Anion Transporting Polypeptides plays a pivotal role in cellular uptake. In this project we will focus on two OATPs namely OATP1A2 and OATP2B1 and the aim will be to evaluate whether dopamine-agonists and dopamine-antagonists are transported by OATP1A2 and OATP2B1, and whether there are differences explaining their differential CNS exposure profile currently explained by limited brain entry. At first, we are going to validate the localization of OATP1A2 and OATP2B1 in the BBB by immunofluorescent staining in human tissue samples. Then we will test whether the transport of the known endogenous substrate estrone 3-sulfate by OATP2B1 and OATP1A2 is influenced by the dopamine-agonists bromocriptine and cabergoline as well as the dopamine-antagonists domperidone and metoclopramide. For compounds exerting an impact on transport rate the respective inhibitory potency will be determined. Transport by OATP2B1 and OATP1A2 will be validated applying either the recently established competitive counterflow protocol or using radiolabeled tracers. Functional evaluation of genetic variants located in the gene SLCO1B7 Research Project | 2 Project MembersIt is widely accepted, that membrane proteins facilitating cellular entry or efflux significantly influence pharmacokinetics of their substrates. The Organic Anion Transporting Polypeptides are one protein family investigated for the contribution to cellular uptake of xenobiotics. In this family of membrane proteins, the OATP1B-subfamily has been focus of various studies in pharmacology. Currently, the OATP1B-family summarizes two members OATP1B1 and OATP1B3. Both are highly expressed in liver and are localized in the sinusoidal membrane of hepatocytes, where it is assumed to govern hepatocellular entry of a variety of compounds in clinical use. We have recently reported on the function and expression of LST-3TM12. Based on our findings this novel member of the OATP1B-family represents a spliced mRNA encoded by SLCO1B3 and SLCO1B7. However, during cloning of the transporter ORF we observed two genetic variants namely rs12321909 and res 73241802, which are both non-synonymous. It is aim of this project to investigate the influence of those two polymorphisms and additional previously reported SNPs on transport function. Detailed analysis of expression and function of the drug transporter rat Oatp2b1 Research Project | 2 Project MembersDrug transporters including the OATPs play a pivotal role in the cellular handling of substrate drugs. The familiy member OATP2B1 exhibits a broad tissue distrubtion with abundance in various organs of known importance in drug absorption and elimination. Thus, OATP2B1 is considered a determinant of pharmacokinetics of its substrates. In the process of drug development new molecular entities are screened for interactions with relevant drug transporters using overexpressing cellular systems. The findings of those in vitro studies mainly conducted with human transporters are supplemented by in vivo animal studies conducted to provide information on pharmacokinetics and metabolic stability. However, due to interspecies divergence in transporter expression and function extrapolation of those findings to humans in preparation of the clinical assessment is challenging. In the herein proposed study I will focus on the expression and functional comparison of rat and human Oatp2b1 (OATP2B1). At first, a detailed analysis on expression levels and locaclisation in various tissues will be conducted, thereby adding information to preliminary data showing a similar expression pattern of both transporters in various tissues. During the project a cell line overexpressing the transporter will be established in order to screen known substrates of OATP2B1 for interaction with the rat transporter. In addition to these in vitro experiments pharmacokinetic studies in rats will be performed to determine the contribution of Oatp2b1 to pharmacokinetics of identified substrates and inhibitors. The second part of the study will investigate structure function relation of OATP2B1. Indeed, even if preliminary data suggested a similar tissue distribution we observed pronounced differences in uptake of the known OATP2B1 substrate estrone 3-sulfate. This observation in addition to in silico data showing differences in the amino acid sequence encompassing transmembrane domain (TMD) 9, the extracellular loop (ECL) 5, and TMD10 suggests that gradual humanization of rat Oatp2b1 in this area following functional characterization may provide insights in the structure function relation of human OATP2B1. Taken together, this study will contribute to a profound understanding of rat Oatp2b1 (in comparsion to the human transporter) thereby providing information necessary for extrapolation of data obtained during the clinical assessment in drug development. Genetic Testing: Factors Influencing Public Interest and Attitudes Research Project | 3 Project MembersThe Human Genome Project, which started in the 1990s, achieved its initial aim of sequencing the first human genome in 2003. Since then, sequencing technologies have improved significantly, making DNA sequencing faster, easier and cheaper. Sequencing of pre-defined gene panels as well as Whole Exome Sequencing has arrived in the medical practise in many countries, Switzerland among them. Alongside other applications such as prenatal genetic diagnostics or for monogenetic rare diseases, genetic testing for cancer has been used frequently. Alongside with these genetic advances in both research and clinical practise, Ethical, Legal and Social Issues (ELSI) of genetics have been widely raised, discussed and studied. The increase in genetic medical knowledge and technologies bring many challenges that need to be addressed. This project aims to contribute to this issue by investigating factors influencing public interest and attitudes towards genetic testing with the following research questions: (1) Investigate what the most important print media from the German and the French speaking part of Switzerland have written about chosen aspects of genetic testing in the last four years; and (2) investigate attitudes, reasons and information strategies of people requesting a predictive genetic test. By conducting a media content analysis of Swiss online media we aim to assess the publicly discussed aspects about genetic testing in Switzerland. It can to some extent reflect public awareness of the different aspects on genetic testing, and might uncover possible differences between the German and French speaking part of Switzerland. In addition, this analysis is helpful for health personnel and policy makers to identify misconceptions and need for public education to foster evidence-based discussion of these topics in the (Swiss) society. Attitudes, reasons and strategies for handling decisions connected to predictive genetic testing for inherited cancer risk will be investigated by interviewing people using or interested in these genetic tests. Patient interviews can uncover attitudes and motivations for testing, as well as so far unknown factors that help patients through personal decisions and testing procedures. We decided to focus on patients here, however in a next step the interest, knowledge and attitudes of other players such as general practitioners, specialized medical doctors or health insurances will also be of interest in that context. With the results of this study, we thus aim to establish a basis for further research on information strategies, interest and attitudes of people in Switzerland towards genetic testing. Untersuchungen zur Rolle des Arzneimitteltransporters OATP1B3 pankreatischen Wirkung von CCK-8 und Sulfonylharnstoffen Research Project | 1 Project MembersMembranständige Transportproteine, welche die zelluläre Aufnahme vermitteln, spielen eine entscheidende Rolle in der Kontrolle der intrazellulären Verfügbarkeit ihrer Substrate, und können so die Wirkungen dieser ausschlaggebend beeinflussen. Eine Familie von Aufnahmetransportern ist die der Organic Anion Transporting Polypeptides . Im Mittelpunkt pharmakologischer Forschung stehen die beiden Mitglieder der OATP1B-Subfamilie, welche eine Vielzahl von Arzneimitteln als Substrate erkennt. In Vorarbeiten zu diesem Antrag konnte die Expression des Aufnahmetransporters OATP1B3 in den Insulin-produzierenden Inselzellen des humanen Pankreas nachgewiesen werden. In Assoziation mit der vorhergehenden Beschreibung des intestinal gebildeten Inkretins Choleystokinin-8 (CCK-8) als spezifisches endogenes Substrat und dem Nachweis der Interaktion von Sulfonylharnstoffen mit OATP1B3 stellt sich nun die Frage nach der Rolle dieses Aufnahmetransporters in der Physiologie und Pharmakologie des humanen Pankreas. Um dieser Frage nachzugehen soll ein glukose-sensitives insulinproduzierendes OATP1B3-überexprimierendes Zellmodel etabliert und nachfolgend funktionell charakterisiert werden. Betrachtet wird der Einfluss des Transportproteins auf die zellulären Effekte des CCK-8 sowie der Sulfonylharnstoffe. Im Mittelpunkt der in vitro Untersuchungen steht der Einfluss auf die insulinotrope Wirkung dieser endogenen bzw. exogenen Substanzen, sowie die mögliche Interaktion von Sulfonylharnstoffen mit der physiologischen Wirkung des CCK-8. Neben diesen zellulären Effekten soll auch der direkte Transport der Sulfonylharnstoffe durch OATP1B3 nachgewiesen werden. Grundlage eines translationalen Ansatzes ist die Tatsache, dass in vorhergehenden Untersuchungen häufig auftretende genetische Varianten mit funktioneller Relevanz identifiziert wurden. Im Rahmen einer Studie an gesunden Probanden soll der Einfluss dieser auf die CCK-8 Effekte in vivo untersucht werden. Hierzu wird eine zweiarmige Studie durchgeführt. In der ersten Studienphase soll der Einfluss der genetischen Varianten des Transporters auf die systemische Verfügbarkeit intestinal gebildeten CCK-8 nach Einnahme einer standardisierten Mahlzeit erfasst werden. Von Bedeutung scheint hier die zusätzliche hepatische Expression des Transportproteins, welche Einfluss auf die systemische Verfügbarkeit des CCK-8 haben könnte. In der zweiten Studienphase soll der Einfluss genetischer Varianten des OATP1B3 auf die insulinotrope Wirkung des CCK-8 in den gesunden Probanden untersucht werden, dies erfolgt nach Einnahme von 75g Glukose. Bestimmt werden soll nicht nur der Spiegel des CCK-8, sondern auch die Spiegel des Insulins und weitere regulative Hormone des Glukosehaushaltes. Das Studienprotokoll wurde durch das lokale Ethikkomitee positiv begutachtet. Die Durchführung der Studie erfolgt in enger Zusammenarbeit mit dem Institut für Klinische Pharmakologie der Universitätsmedizin Greifswald. 1 1 OverviewMembersPublicationsProjects & Collaborations
Projects & Collaborations 8 foundShow per page10 10 20 50 Specificity, selectivity and pharmacokinetics of compstatin: a comprehensive multidisciplinary analysis Research Project | 6 Project MembersThe complement system plays a major role in innate immunity as it confers immune surveillance and first-line defense against non- or altered-self entities such as microbes or apoptotic cells. Yet, misguided complement activation may trigger or contribute to severe clinical conditions or complications, including autoimmune, hemolytic, inflammatory and age-related disorders and transplant rejection (PMID) [1]. Owing to its cascade organization, involving ~50 plasma proteins, receptors and enzymes, complement provides multiple points for novel pharmacological intervention [2]. However, few complement-targeted drugs have reached the clinic, and the available options primarily target peripheral steps in cascade initiation or effector generation. For many acute-phase or multifactorial complement disorders, blocking the activation of the central complement component C3 is considered important [3]. Derivatives of compstatin, a peptidic inhibitor of C3 activation [4], are the most advanced compounds in this class, with two candidate drugs being evaluated in clinical trials. However, its narrow species-specificity for primate C3 currently restricts a broader exploration of potential benefits of C3 inhibition in various established animal models of complement disorders. Furthermore, despite considerable progress in structure optimization, some pharmacokinetic and physicochemical properties of the compstatin class remain to be improved to fully unleash its unique therapeutic potential. The main objective of this project is to understand target binding and complement inhibition by compstatin in the human system at the atomic level and identify key determinants of its narrow species specificity. We will utilize this knowledge for designing compstatin analogs that recognize non-primate C3 and, for example, inhibit mouse, rat or pig complement. Simultaneously, we will assess compstatin's target selectivity for C3 over the orthologous C4 and C5 proteins and explore options for achieving C4-, C5- or pan-specific inhibitors for research or clinical applications. Finally, we will analyze and optimize the pharmacokinetic properties of compstatin with special emphasis on solubility and bioavailability. The proposed rationalization and optimization efforts will be driven by well-established in silico simulation techniques such as molecular dynamics simulations, free energy methods, homology modeling, and post-MD analyses, supported by novel approaches based on deep learning (Prof. Markus Lill, Computational Pharmacy). Thanks to project collaborations with strong experimental groups, in silico findings will be experimentally verified by employing peptide synthesis and characterization, chemical modification and labeling, and target binding and functional assays in vitro (Prof. Daniel Ricklin, Molecular Pharmacy) as well as pre-clinical assessments of cellular permeability in vitro and in vivo (Prof. Henriette Meyer zu Schwabedissen, Biopharmacy; all at University of Basel). Our studies are expected to extend preclinical evaluation options of compstatin-based drugs in animal models and enhance their pharmacokinetic profile, thereby facilitating clinical development of this important inhibitor class. Selectivity studies with C4/C5 may provide insight into complement activation and potentially reveal novel inhibitors. Finally, atomic level insight into the structure-activity/property relationships of cyclic peptides may be used for the design of this compound type in general. [1] Ricklin, D.; Reis, E. S.; Lambris, J. D. Complement in Disease: A Defence System Turning Offensive. Nat. Rev. Nephrol. 2016, 12 (7), 383-401. https://doi.org/10.1038/nrneph.2016.70. [2] Mastellos, D.C., Ricklin, D. & Lambris, J.D. Clinical promise of next-generation complement therapeutics. Nat Rev Drug Discov 18, 707-729 (2019). https://doi.org/10.1038/s41573-019-0031-6 [3] Mastellos, D. C.; Reis, E. S.; Ricklin, D.; Smith, R. J.; Lambris, J. D. Complement C3-Targeted Therapy: Replacing Long-Held Assertions with Evidence-Based Discovery. Trends Immunol. 2017, 38 (6), 383-394. https://doi.org/10.1016/j.it.2017.03.003. [4] Mastellos, D. C.; Yancopoulou, D.; Kokkinos, P.; Huber-Lang, M.; Hajishengallis, G.; Biglarnia, A. R.; Lupu, F.; Nilsson, B.; Risitano, A. M.; Ricklin, D.; Lambris, J. D. Compstatin: A C3-Targeted Complement Inhibitor Reaching Its Prime for Bedside Intervention. Eur. J. Clin. Invest. 2015, 45 (4), 423-440. https://doi.org/10.1111/eci.12419. Investigations on the impact of herbal extracts on intestinal handling of histamine Research Project | 3 Project MembersHistamine intolerance (HIT) is a common diagnosis with an estimated prevalence of 1% in the Western population. Patients suffering from HIT exposed to histamine present with various symptoms such as rhinal congestion, headache, tachycardia, diarrhea, urticaria, and eventually bronchoconstriction. Food-derived histamine is modulated by different mechanisms in the intestine. Two intestinal enzymes, diamine oxidase (DAO) and histamine-N-methyltransferase (HNMT), are reported to metabolize histamine. Moreover, transport proteins, such as Organic Cation Transporter 3 (OCT3) or Plasma Membrane Monoamine Transporters (PMAT), are believed to contribute to the transmembrane transport and thus the overall handling of histamine. Using an immortalized cell line originating from colon adenocarcinoma, Caco-2, we aim to elucidate the influence of herbal remedies used in clinics for their influence on the intestinal handling of histamine. In pre-experiments we successfully validated the expression of DAO and HNMT in Caco-2 cells. In a dose-finding experiment, we will first test a dilution series of herbal extracts in cell viability assays in order to exclude a negative effect on Caco-2 cell viability. Next we will investigate the effect of different concentrations of herbal extracts on DAO and HNMT mRNA and protein expression by real-time qPCR and Western blot analysis, respectively. Previously, it has been reported that Caco-2 cells exposed to heparin showed a significant increase in DAO release and DAO enzymatic activity. Accordingly, we will examine the effect of herbal extract on DAO content and DAO activity in the enriched secretome of Caco-2 cells applying Western blot analysis and a fluorometric DAO enzyme activity assay, respectively. Since herbal extract may potentially interact with the transcellular transport of food-derived histamine in the intestine, we will apply Caco-2 transwell transport studies to assess the influence on the uptake of radioactive [3H]-histamine as a tracer. Adding herbal extracts to the apical side of the transwell (representing the luminal side of the intestine) we will determine the apical-to-basal as well as the basal-to-apical transfer of histamine. Concluding we will perform transport interaction experiments testing for the impact of histamine handling by OCT3 or PMAT in presence or absence of herbal extracts. To investigate the role of OCT3 we will apply a MDCKII cell line stably expressing OCT3 (MDCKII-OCT3) and readily available in our laboratory. PMAT will be cloned from human brain cDNA. We will then use the vaccinia virus-assisted expression system to transiently overexpress PMAT in HeLa cells. Optimising paediatric dosing regimens based on a clinical data warehouse SwissPKcdw Research Project | 4 Project MembersThe project will build the SwissPharmacoKinetics clinical data warehouse SwissPK cdw , with encoded clinical, pharmacokinetic, physiological and genetic data from Swiss Children's Hospitals (real-world data). Within the project the collaborating groups will focus on the patients with highest need for optimised dosage regimens, namely the paediatric patients, and will include a pre-defined list of 1-3 drugs. The long-term goal beyond the funding period is to establish a dynamic, steadily growing CDW for any drug and any patient cohort. It is aim to significantly extend based on analytical evidence the current expert-opinio-only recommendations for drug dosage in paediatrics and to identify covariates which best predict the pharmacokinetics in children, including physiological factors, genetic polymorphisms in ADMET-relevant genes, disease-related factors and co-medication. Studies on the role of OATP1A2 and OATP2B1 in dopamine-agonist and -antagonist transport across the blood-brain barrier Research Project | 2 Project MembersIn order to enter the brain a compound has to cross the blood brain barrier (BBB), which efficiently protects the central nervous system from xenobiotic exposure. However, the protection is substrate specific as there are some compounds, which exert their pharmacological effect in the brain and are certainly able to cross the membrane, while others do not even if they are structurally related. It is widely known that membrane proteins are involved in cellular efflux and uptake, whereby influencing transcellular transport. The family of Organic Anion Transporting Polypeptides plays a pivotal role in cellular uptake. In this project we will focus on two OATPs namely OATP1A2 and OATP2B1 and the aim will be to evaluate whether dopamine-agonists and dopamine-antagonists are transported by OATP1A2 and OATP2B1, and whether there are differences explaining their differential CNS exposure profile currently explained by limited brain entry. At first, we are going to validate the localization of OATP1A2 and OATP2B1 in the BBB by immunofluorescent staining in human tissue samples. Then we will test whether the transport of the known endogenous substrate estrone 3-sulfate by OATP2B1 and OATP1A2 is influenced by the dopamine-agonists bromocriptine and cabergoline as well as the dopamine-antagonists domperidone and metoclopramide. For compounds exerting an impact on transport rate the respective inhibitory potency will be determined. Transport by OATP2B1 and OATP1A2 will be validated applying either the recently established competitive counterflow protocol or using radiolabeled tracers. Functional evaluation of genetic variants located in the gene SLCO1B7 Research Project | 2 Project MembersIt is widely accepted, that membrane proteins facilitating cellular entry or efflux significantly influence pharmacokinetics of their substrates. The Organic Anion Transporting Polypeptides are one protein family investigated for the contribution to cellular uptake of xenobiotics. In this family of membrane proteins, the OATP1B-subfamily has been focus of various studies in pharmacology. Currently, the OATP1B-family summarizes two members OATP1B1 and OATP1B3. Both are highly expressed in liver and are localized in the sinusoidal membrane of hepatocytes, where it is assumed to govern hepatocellular entry of a variety of compounds in clinical use. We have recently reported on the function and expression of LST-3TM12. Based on our findings this novel member of the OATP1B-family represents a spliced mRNA encoded by SLCO1B3 and SLCO1B7. However, during cloning of the transporter ORF we observed two genetic variants namely rs12321909 and res 73241802, which are both non-synonymous. It is aim of this project to investigate the influence of those two polymorphisms and additional previously reported SNPs on transport function. Detailed analysis of expression and function of the drug transporter rat Oatp2b1 Research Project | 2 Project MembersDrug transporters including the OATPs play a pivotal role in the cellular handling of substrate drugs. The familiy member OATP2B1 exhibits a broad tissue distrubtion with abundance in various organs of known importance in drug absorption and elimination. Thus, OATP2B1 is considered a determinant of pharmacokinetics of its substrates. In the process of drug development new molecular entities are screened for interactions with relevant drug transporters using overexpressing cellular systems. The findings of those in vitro studies mainly conducted with human transporters are supplemented by in vivo animal studies conducted to provide information on pharmacokinetics and metabolic stability. However, due to interspecies divergence in transporter expression and function extrapolation of those findings to humans in preparation of the clinical assessment is challenging. In the herein proposed study I will focus on the expression and functional comparison of rat and human Oatp2b1 (OATP2B1). At first, a detailed analysis on expression levels and locaclisation in various tissues will be conducted, thereby adding information to preliminary data showing a similar expression pattern of both transporters in various tissues. During the project a cell line overexpressing the transporter will be established in order to screen known substrates of OATP2B1 for interaction with the rat transporter. In addition to these in vitro experiments pharmacokinetic studies in rats will be performed to determine the contribution of Oatp2b1 to pharmacokinetics of identified substrates and inhibitors. The second part of the study will investigate structure function relation of OATP2B1. Indeed, even if preliminary data suggested a similar tissue distribution we observed pronounced differences in uptake of the known OATP2B1 substrate estrone 3-sulfate. This observation in addition to in silico data showing differences in the amino acid sequence encompassing transmembrane domain (TMD) 9, the extracellular loop (ECL) 5, and TMD10 suggests that gradual humanization of rat Oatp2b1 in this area following functional characterization may provide insights in the structure function relation of human OATP2B1. Taken together, this study will contribute to a profound understanding of rat Oatp2b1 (in comparsion to the human transporter) thereby providing information necessary for extrapolation of data obtained during the clinical assessment in drug development. Genetic Testing: Factors Influencing Public Interest and Attitudes Research Project | 3 Project MembersThe Human Genome Project, which started in the 1990s, achieved its initial aim of sequencing the first human genome in 2003. Since then, sequencing technologies have improved significantly, making DNA sequencing faster, easier and cheaper. Sequencing of pre-defined gene panels as well as Whole Exome Sequencing has arrived in the medical practise in many countries, Switzerland among them. Alongside other applications such as prenatal genetic diagnostics or for monogenetic rare diseases, genetic testing for cancer has been used frequently. Alongside with these genetic advances in both research and clinical practise, Ethical, Legal and Social Issues (ELSI) of genetics have been widely raised, discussed and studied. The increase in genetic medical knowledge and technologies bring many challenges that need to be addressed. This project aims to contribute to this issue by investigating factors influencing public interest and attitudes towards genetic testing with the following research questions: (1) Investigate what the most important print media from the German and the French speaking part of Switzerland have written about chosen aspects of genetic testing in the last four years; and (2) investigate attitudes, reasons and information strategies of people requesting a predictive genetic test. By conducting a media content analysis of Swiss online media we aim to assess the publicly discussed aspects about genetic testing in Switzerland. It can to some extent reflect public awareness of the different aspects on genetic testing, and might uncover possible differences between the German and French speaking part of Switzerland. In addition, this analysis is helpful for health personnel and policy makers to identify misconceptions and need for public education to foster evidence-based discussion of these topics in the (Swiss) society. Attitudes, reasons and strategies for handling decisions connected to predictive genetic testing for inherited cancer risk will be investigated by interviewing people using or interested in these genetic tests. Patient interviews can uncover attitudes and motivations for testing, as well as so far unknown factors that help patients through personal decisions and testing procedures. We decided to focus on patients here, however in a next step the interest, knowledge and attitudes of other players such as general practitioners, specialized medical doctors or health insurances will also be of interest in that context. With the results of this study, we thus aim to establish a basis for further research on information strategies, interest and attitudes of people in Switzerland towards genetic testing. Untersuchungen zur Rolle des Arzneimitteltransporters OATP1B3 pankreatischen Wirkung von CCK-8 und Sulfonylharnstoffen Research Project | 1 Project MembersMembranständige Transportproteine, welche die zelluläre Aufnahme vermitteln, spielen eine entscheidende Rolle in der Kontrolle der intrazellulären Verfügbarkeit ihrer Substrate, und können so die Wirkungen dieser ausschlaggebend beeinflussen. Eine Familie von Aufnahmetransportern ist die der Organic Anion Transporting Polypeptides . Im Mittelpunkt pharmakologischer Forschung stehen die beiden Mitglieder der OATP1B-Subfamilie, welche eine Vielzahl von Arzneimitteln als Substrate erkennt. In Vorarbeiten zu diesem Antrag konnte die Expression des Aufnahmetransporters OATP1B3 in den Insulin-produzierenden Inselzellen des humanen Pankreas nachgewiesen werden. In Assoziation mit der vorhergehenden Beschreibung des intestinal gebildeten Inkretins Choleystokinin-8 (CCK-8) als spezifisches endogenes Substrat und dem Nachweis der Interaktion von Sulfonylharnstoffen mit OATP1B3 stellt sich nun die Frage nach der Rolle dieses Aufnahmetransporters in der Physiologie und Pharmakologie des humanen Pankreas. Um dieser Frage nachzugehen soll ein glukose-sensitives insulinproduzierendes OATP1B3-überexprimierendes Zellmodel etabliert und nachfolgend funktionell charakterisiert werden. Betrachtet wird der Einfluss des Transportproteins auf die zellulären Effekte des CCK-8 sowie der Sulfonylharnstoffe. Im Mittelpunkt der in vitro Untersuchungen steht der Einfluss auf die insulinotrope Wirkung dieser endogenen bzw. exogenen Substanzen, sowie die mögliche Interaktion von Sulfonylharnstoffen mit der physiologischen Wirkung des CCK-8. Neben diesen zellulären Effekten soll auch der direkte Transport der Sulfonylharnstoffe durch OATP1B3 nachgewiesen werden. Grundlage eines translationalen Ansatzes ist die Tatsache, dass in vorhergehenden Untersuchungen häufig auftretende genetische Varianten mit funktioneller Relevanz identifiziert wurden. Im Rahmen einer Studie an gesunden Probanden soll der Einfluss dieser auf die CCK-8 Effekte in vivo untersucht werden. Hierzu wird eine zweiarmige Studie durchgeführt. In der ersten Studienphase soll der Einfluss der genetischen Varianten des Transporters auf die systemische Verfügbarkeit intestinal gebildeten CCK-8 nach Einnahme einer standardisierten Mahlzeit erfasst werden. Von Bedeutung scheint hier die zusätzliche hepatische Expression des Transportproteins, welche Einfluss auf die systemische Verfügbarkeit des CCK-8 haben könnte. In der zweiten Studienphase soll der Einfluss genetischer Varianten des OATP1B3 auf die insulinotrope Wirkung des CCK-8 in den gesunden Probanden untersucht werden, dies erfolgt nach Einnahme von 75g Glukose. Bestimmt werden soll nicht nur der Spiegel des CCK-8, sondern auch die Spiegel des Insulins und weitere regulative Hormone des Glukosehaushaltes. Das Studienprotokoll wurde durch das lokale Ethikkomitee positiv begutachtet. Die Durchführung der Studie erfolgt in enger Zusammenarbeit mit dem Institut für Klinische Pharmakologie der Universitätsmedizin Greifswald. 1 1
Specificity, selectivity and pharmacokinetics of compstatin: a comprehensive multidisciplinary analysis Research Project | 6 Project MembersThe complement system plays a major role in innate immunity as it confers immune surveillance and first-line defense against non- or altered-self entities such as microbes or apoptotic cells. Yet, misguided complement activation may trigger or contribute to severe clinical conditions or complications, including autoimmune, hemolytic, inflammatory and age-related disorders and transplant rejection (PMID) [1]. Owing to its cascade organization, involving ~50 plasma proteins, receptors and enzymes, complement provides multiple points for novel pharmacological intervention [2]. However, few complement-targeted drugs have reached the clinic, and the available options primarily target peripheral steps in cascade initiation or effector generation. For many acute-phase or multifactorial complement disorders, blocking the activation of the central complement component C3 is considered important [3]. Derivatives of compstatin, a peptidic inhibitor of C3 activation [4], are the most advanced compounds in this class, with two candidate drugs being evaluated in clinical trials. However, its narrow species-specificity for primate C3 currently restricts a broader exploration of potential benefits of C3 inhibition in various established animal models of complement disorders. Furthermore, despite considerable progress in structure optimization, some pharmacokinetic and physicochemical properties of the compstatin class remain to be improved to fully unleash its unique therapeutic potential. The main objective of this project is to understand target binding and complement inhibition by compstatin in the human system at the atomic level and identify key determinants of its narrow species specificity. We will utilize this knowledge for designing compstatin analogs that recognize non-primate C3 and, for example, inhibit mouse, rat or pig complement. Simultaneously, we will assess compstatin's target selectivity for C3 over the orthologous C4 and C5 proteins and explore options for achieving C4-, C5- or pan-specific inhibitors for research or clinical applications. Finally, we will analyze and optimize the pharmacokinetic properties of compstatin with special emphasis on solubility and bioavailability. The proposed rationalization and optimization efforts will be driven by well-established in silico simulation techniques such as molecular dynamics simulations, free energy methods, homology modeling, and post-MD analyses, supported by novel approaches based on deep learning (Prof. Markus Lill, Computational Pharmacy). Thanks to project collaborations with strong experimental groups, in silico findings will be experimentally verified by employing peptide synthesis and characterization, chemical modification and labeling, and target binding and functional assays in vitro (Prof. Daniel Ricklin, Molecular Pharmacy) as well as pre-clinical assessments of cellular permeability in vitro and in vivo (Prof. Henriette Meyer zu Schwabedissen, Biopharmacy; all at University of Basel). Our studies are expected to extend preclinical evaluation options of compstatin-based drugs in animal models and enhance their pharmacokinetic profile, thereby facilitating clinical development of this important inhibitor class. Selectivity studies with C4/C5 may provide insight into complement activation and potentially reveal novel inhibitors. Finally, atomic level insight into the structure-activity/property relationships of cyclic peptides may be used for the design of this compound type in general. [1] Ricklin, D.; Reis, E. S.; Lambris, J. D. Complement in Disease: A Defence System Turning Offensive. Nat. Rev. Nephrol. 2016, 12 (7), 383-401. https://doi.org/10.1038/nrneph.2016.70. [2] Mastellos, D.C., Ricklin, D. & Lambris, J.D. Clinical promise of next-generation complement therapeutics. Nat Rev Drug Discov 18, 707-729 (2019). https://doi.org/10.1038/s41573-019-0031-6 [3] Mastellos, D. C.; Reis, E. S.; Ricklin, D.; Smith, R. J.; Lambris, J. D. Complement C3-Targeted Therapy: Replacing Long-Held Assertions with Evidence-Based Discovery. Trends Immunol. 2017, 38 (6), 383-394. https://doi.org/10.1016/j.it.2017.03.003. [4] Mastellos, D. C.; Yancopoulou, D.; Kokkinos, P.; Huber-Lang, M.; Hajishengallis, G.; Biglarnia, A. R.; Lupu, F.; Nilsson, B.; Risitano, A. M.; Ricklin, D.; Lambris, J. D. Compstatin: A C3-Targeted Complement Inhibitor Reaching Its Prime for Bedside Intervention. Eur. J. Clin. Invest. 2015, 45 (4), 423-440. https://doi.org/10.1111/eci.12419.
Investigations on the impact of herbal extracts on intestinal handling of histamine Research Project | 3 Project MembersHistamine intolerance (HIT) is a common diagnosis with an estimated prevalence of 1% in the Western population. Patients suffering from HIT exposed to histamine present with various symptoms such as rhinal congestion, headache, tachycardia, diarrhea, urticaria, and eventually bronchoconstriction. Food-derived histamine is modulated by different mechanisms in the intestine. Two intestinal enzymes, diamine oxidase (DAO) and histamine-N-methyltransferase (HNMT), are reported to metabolize histamine. Moreover, transport proteins, such as Organic Cation Transporter 3 (OCT3) or Plasma Membrane Monoamine Transporters (PMAT), are believed to contribute to the transmembrane transport and thus the overall handling of histamine. Using an immortalized cell line originating from colon adenocarcinoma, Caco-2, we aim to elucidate the influence of herbal remedies used in clinics for their influence on the intestinal handling of histamine. In pre-experiments we successfully validated the expression of DAO and HNMT in Caco-2 cells. In a dose-finding experiment, we will first test a dilution series of herbal extracts in cell viability assays in order to exclude a negative effect on Caco-2 cell viability. Next we will investigate the effect of different concentrations of herbal extracts on DAO and HNMT mRNA and protein expression by real-time qPCR and Western blot analysis, respectively. Previously, it has been reported that Caco-2 cells exposed to heparin showed a significant increase in DAO release and DAO enzymatic activity. Accordingly, we will examine the effect of herbal extract on DAO content and DAO activity in the enriched secretome of Caco-2 cells applying Western blot analysis and a fluorometric DAO enzyme activity assay, respectively. Since herbal extract may potentially interact with the transcellular transport of food-derived histamine in the intestine, we will apply Caco-2 transwell transport studies to assess the influence on the uptake of radioactive [3H]-histamine as a tracer. Adding herbal extracts to the apical side of the transwell (representing the luminal side of the intestine) we will determine the apical-to-basal as well as the basal-to-apical transfer of histamine. Concluding we will perform transport interaction experiments testing for the impact of histamine handling by OCT3 or PMAT in presence or absence of herbal extracts. To investigate the role of OCT3 we will apply a MDCKII cell line stably expressing OCT3 (MDCKII-OCT3) and readily available in our laboratory. PMAT will be cloned from human brain cDNA. We will then use the vaccinia virus-assisted expression system to transiently overexpress PMAT in HeLa cells.
Optimising paediatric dosing regimens based on a clinical data warehouse SwissPKcdw Research Project | 4 Project MembersThe project will build the SwissPharmacoKinetics clinical data warehouse SwissPK cdw , with encoded clinical, pharmacokinetic, physiological and genetic data from Swiss Children's Hospitals (real-world data). Within the project the collaborating groups will focus on the patients with highest need for optimised dosage regimens, namely the paediatric patients, and will include a pre-defined list of 1-3 drugs. The long-term goal beyond the funding period is to establish a dynamic, steadily growing CDW for any drug and any patient cohort. It is aim to significantly extend based on analytical evidence the current expert-opinio-only recommendations for drug dosage in paediatrics and to identify covariates which best predict the pharmacokinetics in children, including physiological factors, genetic polymorphisms in ADMET-relevant genes, disease-related factors and co-medication.
Studies on the role of OATP1A2 and OATP2B1 in dopamine-agonist and -antagonist transport across the blood-brain barrier Research Project | 2 Project MembersIn order to enter the brain a compound has to cross the blood brain barrier (BBB), which efficiently protects the central nervous system from xenobiotic exposure. However, the protection is substrate specific as there are some compounds, which exert their pharmacological effect in the brain and are certainly able to cross the membrane, while others do not even if they are structurally related. It is widely known that membrane proteins are involved in cellular efflux and uptake, whereby influencing transcellular transport. The family of Organic Anion Transporting Polypeptides plays a pivotal role in cellular uptake. In this project we will focus on two OATPs namely OATP1A2 and OATP2B1 and the aim will be to evaluate whether dopamine-agonists and dopamine-antagonists are transported by OATP1A2 and OATP2B1, and whether there are differences explaining their differential CNS exposure profile currently explained by limited brain entry. At first, we are going to validate the localization of OATP1A2 and OATP2B1 in the BBB by immunofluorescent staining in human tissue samples. Then we will test whether the transport of the known endogenous substrate estrone 3-sulfate by OATP2B1 and OATP1A2 is influenced by the dopamine-agonists bromocriptine and cabergoline as well as the dopamine-antagonists domperidone and metoclopramide. For compounds exerting an impact on transport rate the respective inhibitory potency will be determined. Transport by OATP2B1 and OATP1A2 will be validated applying either the recently established competitive counterflow protocol or using radiolabeled tracers.
Functional evaluation of genetic variants located in the gene SLCO1B7 Research Project | 2 Project MembersIt is widely accepted, that membrane proteins facilitating cellular entry or efflux significantly influence pharmacokinetics of their substrates. The Organic Anion Transporting Polypeptides are one protein family investigated for the contribution to cellular uptake of xenobiotics. In this family of membrane proteins, the OATP1B-subfamily has been focus of various studies in pharmacology. Currently, the OATP1B-family summarizes two members OATP1B1 and OATP1B3. Both are highly expressed in liver and are localized in the sinusoidal membrane of hepatocytes, where it is assumed to govern hepatocellular entry of a variety of compounds in clinical use. We have recently reported on the function and expression of LST-3TM12. Based on our findings this novel member of the OATP1B-family represents a spliced mRNA encoded by SLCO1B3 and SLCO1B7. However, during cloning of the transporter ORF we observed two genetic variants namely rs12321909 and res 73241802, which are both non-synonymous. It is aim of this project to investigate the influence of those two polymorphisms and additional previously reported SNPs on transport function.
Detailed analysis of expression and function of the drug transporter rat Oatp2b1 Research Project | 2 Project MembersDrug transporters including the OATPs play a pivotal role in the cellular handling of substrate drugs. The familiy member OATP2B1 exhibits a broad tissue distrubtion with abundance in various organs of known importance in drug absorption and elimination. Thus, OATP2B1 is considered a determinant of pharmacokinetics of its substrates. In the process of drug development new molecular entities are screened for interactions with relevant drug transporters using overexpressing cellular systems. The findings of those in vitro studies mainly conducted with human transporters are supplemented by in vivo animal studies conducted to provide information on pharmacokinetics and metabolic stability. However, due to interspecies divergence in transporter expression and function extrapolation of those findings to humans in preparation of the clinical assessment is challenging. In the herein proposed study I will focus on the expression and functional comparison of rat and human Oatp2b1 (OATP2B1). At first, a detailed analysis on expression levels and locaclisation in various tissues will be conducted, thereby adding information to preliminary data showing a similar expression pattern of both transporters in various tissues. During the project a cell line overexpressing the transporter will be established in order to screen known substrates of OATP2B1 for interaction with the rat transporter. In addition to these in vitro experiments pharmacokinetic studies in rats will be performed to determine the contribution of Oatp2b1 to pharmacokinetics of identified substrates and inhibitors. The second part of the study will investigate structure function relation of OATP2B1. Indeed, even if preliminary data suggested a similar tissue distribution we observed pronounced differences in uptake of the known OATP2B1 substrate estrone 3-sulfate. This observation in addition to in silico data showing differences in the amino acid sequence encompassing transmembrane domain (TMD) 9, the extracellular loop (ECL) 5, and TMD10 suggests that gradual humanization of rat Oatp2b1 in this area following functional characterization may provide insights in the structure function relation of human OATP2B1. Taken together, this study will contribute to a profound understanding of rat Oatp2b1 (in comparsion to the human transporter) thereby providing information necessary for extrapolation of data obtained during the clinical assessment in drug development.
Genetic Testing: Factors Influencing Public Interest and Attitudes Research Project | 3 Project MembersThe Human Genome Project, which started in the 1990s, achieved its initial aim of sequencing the first human genome in 2003. Since then, sequencing technologies have improved significantly, making DNA sequencing faster, easier and cheaper. Sequencing of pre-defined gene panels as well as Whole Exome Sequencing has arrived in the medical practise in many countries, Switzerland among them. Alongside other applications such as prenatal genetic diagnostics or for monogenetic rare diseases, genetic testing for cancer has been used frequently. Alongside with these genetic advances in both research and clinical practise, Ethical, Legal and Social Issues (ELSI) of genetics have been widely raised, discussed and studied. The increase in genetic medical knowledge and technologies bring many challenges that need to be addressed. This project aims to contribute to this issue by investigating factors influencing public interest and attitudes towards genetic testing with the following research questions: (1) Investigate what the most important print media from the German and the French speaking part of Switzerland have written about chosen aspects of genetic testing in the last four years; and (2) investigate attitudes, reasons and information strategies of people requesting a predictive genetic test. By conducting a media content analysis of Swiss online media we aim to assess the publicly discussed aspects about genetic testing in Switzerland. It can to some extent reflect public awareness of the different aspects on genetic testing, and might uncover possible differences between the German and French speaking part of Switzerland. In addition, this analysis is helpful for health personnel and policy makers to identify misconceptions and need for public education to foster evidence-based discussion of these topics in the (Swiss) society. Attitudes, reasons and strategies for handling decisions connected to predictive genetic testing for inherited cancer risk will be investigated by interviewing people using or interested in these genetic tests. Patient interviews can uncover attitudes and motivations for testing, as well as so far unknown factors that help patients through personal decisions and testing procedures. We decided to focus on patients here, however in a next step the interest, knowledge and attitudes of other players such as general practitioners, specialized medical doctors or health insurances will also be of interest in that context. With the results of this study, we thus aim to establish a basis for further research on information strategies, interest and attitudes of people in Switzerland towards genetic testing.
Untersuchungen zur Rolle des Arzneimitteltransporters OATP1B3 pankreatischen Wirkung von CCK-8 und Sulfonylharnstoffen Research Project | 1 Project MembersMembranständige Transportproteine, welche die zelluläre Aufnahme vermitteln, spielen eine entscheidende Rolle in der Kontrolle der intrazellulären Verfügbarkeit ihrer Substrate, und können so die Wirkungen dieser ausschlaggebend beeinflussen. Eine Familie von Aufnahmetransportern ist die der Organic Anion Transporting Polypeptides . Im Mittelpunkt pharmakologischer Forschung stehen die beiden Mitglieder der OATP1B-Subfamilie, welche eine Vielzahl von Arzneimitteln als Substrate erkennt. In Vorarbeiten zu diesem Antrag konnte die Expression des Aufnahmetransporters OATP1B3 in den Insulin-produzierenden Inselzellen des humanen Pankreas nachgewiesen werden. In Assoziation mit der vorhergehenden Beschreibung des intestinal gebildeten Inkretins Choleystokinin-8 (CCK-8) als spezifisches endogenes Substrat und dem Nachweis der Interaktion von Sulfonylharnstoffen mit OATP1B3 stellt sich nun die Frage nach der Rolle dieses Aufnahmetransporters in der Physiologie und Pharmakologie des humanen Pankreas. Um dieser Frage nachzugehen soll ein glukose-sensitives insulinproduzierendes OATP1B3-überexprimierendes Zellmodel etabliert und nachfolgend funktionell charakterisiert werden. Betrachtet wird der Einfluss des Transportproteins auf die zellulären Effekte des CCK-8 sowie der Sulfonylharnstoffe. Im Mittelpunkt der in vitro Untersuchungen steht der Einfluss auf die insulinotrope Wirkung dieser endogenen bzw. exogenen Substanzen, sowie die mögliche Interaktion von Sulfonylharnstoffen mit der physiologischen Wirkung des CCK-8. Neben diesen zellulären Effekten soll auch der direkte Transport der Sulfonylharnstoffe durch OATP1B3 nachgewiesen werden. Grundlage eines translationalen Ansatzes ist die Tatsache, dass in vorhergehenden Untersuchungen häufig auftretende genetische Varianten mit funktioneller Relevanz identifiziert wurden. Im Rahmen einer Studie an gesunden Probanden soll der Einfluss dieser auf die CCK-8 Effekte in vivo untersucht werden. Hierzu wird eine zweiarmige Studie durchgeführt. In der ersten Studienphase soll der Einfluss der genetischen Varianten des Transporters auf die systemische Verfügbarkeit intestinal gebildeten CCK-8 nach Einnahme einer standardisierten Mahlzeit erfasst werden. Von Bedeutung scheint hier die zusätzliche hepatische Expression des Transportproteins, welche Einfluss auf die systemische Verfügbarkeit des CCK-8 haben könnte. In der zweiten Studienphase soll der Einfluss genetischer Varianten des OATP1B3 auf die insulinotrope Wirkung des CCK-8 in den gesunden Probanden untersucht werden, dies erfolgt nach Einnahme von 75g Glukose. Bestimmt werden soll nicht nur der Spiegel des CCK-8, sondern auch die Spiegel des Insulins und weitere regulative Hormone des Glukosehaushaltes. Das Studienprotokoll wurde durch das lokale Ethikkomitee positiv begutachtet. Die Durchführung der Studie erfolgt in enger Zusammenarbeit mit dem Institut für Klinische Pharmakologie der Universitätsmedizin Greifswald.
