The putative proton-coupled organic cation antiporter is involved in uptake of triptans into human brain capillary endothelial cells

BACKGROUND

Triptans are anti-migraine drugs with a potential central site of action. However, it is not known to what extent triptans cross the blood-brain barrier (BBB). The aim of this study was therefore to determine if triptans pass the brain capillary endothelium and investigate the possible underlying mechanisms with focus on the involvement of the putative proton-coupled organic cation (H+/OC) antiporter. Additionally, we evaluated whether triptans interacted with the efflux transporter, P-glycoprotein (P-gp).

METHODS

We investigated the cellular uptake characteristics of the prototypical H+/OC antiporter substrates, pyrilamine and oxycodone, and seven different triptans in the human brain microvascular endothelial cell line, hCMEC/D3. Triptan interactions with P-gp were studied using the IPEC-J2 MDR1 cell line. Lastly, in vivo neuropharmacokinetic assessment of the unbound brain-to-plasma disposition of eletriptan was conducted in wild type and mdr1a/1b knockout mice.

RESULTS

We demonstrated that most triptans were able to inhibit uptake of the H+/OC antiporter substrate, pyrilamine, with eletriptan emerging as the strongest inhibitor. Eletriptan, almotriptan, and sumatriptan exhibited a pH-dependent uptake into hCMEC/D3 cells. Eletriptan demonstrated saturable uptake kinetics with an apparent Km of 89 ± 38 µM and a Jmax of 2.2 ± 0.7 nmol·min-1·mg protein-1 (n = 3). Bidirectional transport experiments across IPEC-J2 MDR1 monolayers showed that eletriptan is transported by P-gp, thus indicating that eletriptan is both a substrate of the H+/OC antiporter and P-gp. This was further confirmed in vivo, where the unbound brain-to-unbound plasma concentration ratio (Kp,uu) was 0.04 in wild type mice while the ratio rose to 1.32 in mdr1a/1b knockout mice.

CONCLUSIONS

We have demonstrated that the triptan family of compounds possesses affinity for the H+/OC antiporter proposing that the putative H+/OC antiporter plays a role in the BBB transport of triptans, particularly eletriptan. Our in vivo studies indicate that eletriptan is subjected to simultaneous brain uptake and efflux, possibly facilitated by the putative H+/OC antiporter and P-gp, respectively. Our findings offer novel insights into the potential central site of action involved in migraine treatment with triptans and highlight the significance of potential transporter related drug-drug interactions.

Generation of an iPSC-line (BIONi010C-48) with restored P-glycoprotein functionality following transfection with the human MDR1 gene in the AAVS1 locus

The human MDR1 gene encodes the efflux transporter P-glycoprotein, which plays an important part of the blood-brain barrier function of brain microvascular endothelial cells (BMECs). Here, we report the generation of an iPSC line, where a construct of the human MDR1 gene was inserted into the safe-site locus AAVS1. This iPSC line (BIONi010-C-48) shows functional expression of P-gp and can further be differentiated and cultured into electrically tight BMEC-like monolayers exhibiting polarized expression of P-gp in the apical membrane.

Neonatal intestinal mucus barrier changes in response to maturity, inflammation, and sodium decanoate supplementation

The integrity of the intestinal mucus barrier is crucial for human health, as it serves as the body's first line of defense against pathogens. However, postnatal development of the mucus barrier and interactions between maturity and its ability to adapt to external challenges in neonatal infants remain unclear. In this study, we unveil a distinct developmental trajectory of the mucus barrier in preterm piglets, leading to enhanced mucus microstructure and reduced mucus diffusivity compared to term piglets. Notably, we found that necrotizing enterocolitis (NEC) is associated with increased mucus diffusivity of our large pathogen model compound, establishing a direct link between the NEC condition and the mucus barrier. Furthermore, we observed that addition of sodium decanoate had varying effects on mucus diffusivity depending on maturity and health state of the piglets. These findings demonstrate that regulatory mechanisms governing the neonatal mucosal barrier are highly complex and are influenced by age, maturity, and health conditions. Therefore, our results highlight the need for specific therapeutic strategies tailored to each neonatal period to ensure optimal gut health.

Application of a new MDCKII-MDR1 cell model to measure the extent of drug distribution in vitro at equilibrium for prediction of in vivo unbound brain-to-plasma drug distribution

INTRO

Reliable estimates of drug uptake from blood to brain parenchyma are crucial in CNS drug discovery and development. While in vivo Kp,uu,brain estimates are the gold standard for investigating brain drug disposition, animal usage is a limitation to high throughput application. This study investigates an in vitro model using P-gp expressing MDCKII-MDR1 cells for predicting in vivo brain drug penetration.

METHODS

In vitro equilibrium distribution studies were conducted in apical and basolateral solutions with high protein content to estimate Kp,brain and Kp,uu,brain values. The correlation between in vitro and in vivo Kp,brain values for a set of compounds was examined.

RESULTS

We observed a good correlation between in vitro and in vivo Kp,brain values (R2 = 0.69, Slope: 1.6), indicating that the in vitro model could predict in vivo drug brain penetration. The 'unilateral (Uni-L)' in vitro setup correctly classified 5 out of 5 unrestricted compounds and 3 out of 5 restricted compounds. Possible reasons for the observed disparities for some compounds have been discussed, such as difference in transport areas between in vitro and in vivo settings and effect of pH changes.

CONCLUSION

The in vitro assay setup developed in this study holds promise for predicting in vivo drug brain penetration in CNS drug discovery. The correlation between in vitro and in vivo Kp,brain values, underscores that the model may have potential for early-stage screening. With minor refinements, this in vitro approach could reduce the reliance on in vivo experiments, accelerating the pace of CNS drug discovery and promoting a more ethical research approach.

Physical and barrier changes in gastrointestinal mucus induced by the permeation enhancer sodium 8-[(2-hydroxybenzoyl)amino]octanoate (SNAC)

Drug delivery systems (DDS) for oral delivery of peptide drugs contain excipients that facilitate and enhance absorption. However, little knowledge exists on how DDS excipients such as permeation enhancers interact with the gastrointestinal mucus barrier. This study aimed to investigate interactions of the permeation enhancer sodium 8-[(2-hydroxybenzoyl)amino]octanoate (SNAC) with ex vivo porcine intestinal mucus (PIM), ex vivo porcine gastric mucus (PGM), as well as with in vitro biosimilar mucus (BM) by profiling their physical and barrier properties upon exposure to SNAC. Bulk mucus permeability studies using the peptides cyclosporine A and vancomycin, ovalbumin as a model protein, as well as fluorescein-isothiocyanate dextrans (FDs) of different molecular weights and different surface charges were conducted in parallel to mucus retention force studies using a texture analyzer, rheological studies, cryo-scanning electron microscopy (cryo-SEM), and single particle tracking of fluorescence-labelled nanoparticles to investigate the effects of the SNAC-mucus interaction. The exposure of SNAC to PIM increased the mucus retention force, storage modulus, viscosity, increased nanoparticle confinement within PIM as well as decreased the permeation of cyclosporine A and ovalbumin through PIM. Surprisingly, the viscosity of PGM and the permeation of cyclosporine A and ovalbumin through PGM was unaffected by the presence of SNAC, thus the effect of SNAC depended on the regional site that mucus was collected from. In the absence of SNAC, the permeation of different molecular weight and differently charged FDs through PIM was comparable to that through BM. However, while bulk permeation of neither of the FDs through PIM was affected by SNAC, the presence of SNAC decreased the permeation of FD4 and increased the permeation of FD150 kDa through BM. Additionally, and in contrast to observations in PIM, nanoparticle confinement within BM remained unaffected by the presence of SNAC. In conclusion, the present study showed that SNAC altered the physical and barrier properties of PIM, but not of PGM. The effects of SNAC in PIM were not observed in the BM in vitro model. Altogether, the study highlights the need for further understanding how permeation enhancers influence the mucus barrier and illustrates that the selected mucus model for such studies should be chosen with care.

Barrier properties of ex vivo porcine intestinal mucus are highly independent of isolation and storage conditions

Porcine intestinal mucus (PIM) is often utilized as an ex vivo mucus model in mucus interaction studies. However, numerous isolation procedures and storage conditions for PIM are reported, yet their potential impact on preserving the critical properties of PIM remains unknown. This study investigated the effect of isolation procedures (rinsing and anatomical site of mucus isolation) and storage conditions (-20°C, -80°C, snap frozen in liquid nitrogen prior to storage at -80°C, or freeze-dried followed by storage at room temperature and reconstitution) of PIM in regard to the permeation of fluorescein-isothiocyanate-labelled dextran (FD) macromolecules of 4, 40 and 150 kDa, rheological properties as well as pH, osmolality, protein and water content. Rinsing intestines with tap water or phosphate-buffered saline as well as isolating PIM from different regions of the first five meters of the proximal jejunum did not affect the pH or osmolality of isolated PIM. The permeation of FD4, FD40 and FD150 through stored PIM was similar to permeation through fresh PIM. The rheological properties of stored PIM were similar to properties of fresh PIM. Osmolality, protein and water content were similar in stored and fresh PIM whereas pH decreased with 0.3 unit for all stored PIMs. Overall, PIM samples stored at -20°, -80°C, snap frozen or freeze-dried were found to have similar properties to freshly isolated PIM and can all be considered good alternatives to fresh PIM for mucus studies.

Insight Into the Anti-staphylococcal Activity of JBC 1847 at Sub-Inhibitory Concentration

Multidrug-resistant pathogens constitute a serious global issue and, therefore, novel antimicrobials with new modes of action are urgently needed. Here, we investigated the effect of a phenothiazine derivative (JBC 1847) with high antimicrobial activity on Staphylococcus aureus, using a wide range of in vitro assays, flow cytometry, and RNA transcriptomics. The flow cytometry results showed that JBC 1847 rapidly caused depolarization of the cell membrane, while the macromolecule synthesis inhibition assay showed that the synthesis rates of DNA, RNA, cell wall, and proteins, respectively, were strongly decreased. Transcriptome analysis of S. aureus exposed to sub-inhibitory concentrations of JBC 1847 identified a total of 78 downregulated genes, whereas not a single gene was found to be significantly upregulated. Most importantly, there was downregulation of genes involved in adenosintrifosfat (ATP)-dependent pathways, including histidine biosynthesis, which is likely to correlate with the observed lower level of intracellular ATP in JBC 1847-treated cells. Furthermore, we showed that JBC 1847 is bactericidal against both exponentially growing cells and cells in a stationary growth phase. In conclusion, our results showed that the antimicrobial properties of JBC 1847 were primarily caused by depolarization of the cell membrane resulting in dissipation of the proton motive force (PMF), whereby many essential bacterial processes are affected. JBC 1847 resulted in lowered intracellular levels of ATP followed by decreased macromolecule synthesis rate and downregulation of genes essential for the amino acid metabolism in S. aureus. Bacterial compensatory mechanisms for this proposed multi-target activity of JBC 1847 seem to be limited based on the observed very low frequency of resistance toward the compound.

Screening novel CNS drug candidates for P-glycoprotein interactions using the cell line iP-gp: In vitro efflux ratios from iP-gp and MDCK-MDR1 monolayers compared to brain distribution data from mice

Drug efflux by P-glycoprotein (P-gp, ABCB1) is considered as a major obstacle for brain drug delivery for small molecules. P-gp-expressing cell monolayers are used for screening of new drug candidates during early states of drug development. It is, however, uncertain how well the in vitro studies can predict the in vivo P-gp mediated efflux at the blood-brain barrier (BBB). We previously developed a novel cell line of porcine origin, the iP-gp cell line, with high transepithelial resistance and functional expression of human P-gp. The aim of the present study was to evaluate the applicability of the cell line for screening of P-gp interactions of novel drug candidates. For this purpose, bidirectional fluxes of 14 drug candidates were measured in iP-gp cells and in MDCK-MDR1 cells, and compared with pharmacokinetic data obtained in male C57BL/6 mice. The iP-gp cells formed extremely tight monolayers (>15 000 Ω∙cm²) as compared to the MDCK- MDR1 cells (>250 Ω∙cm²) and displayed lower P_app,a-b values. The efflux ratios obtained with iP-gp and MDCK-MDR1 monolayers correlated with K_p,uu,brain values from the in vivo studies, where compounds with the lowest K_p,uu,brain generally displayed the highest efflux ratios. 12 of the tested compounds displayed a poor BBB penetration in mice as judged by K_p,uu less than 1. Of these compounds, nine compounds were categorized as P-gp substrates in the iP-gp screening, whereas analysis of data estimated in MDCK-MDR1 cells indicated four compounds as potential substrates. The results suggest that the iP-gp cell model may be a sensitive and useful screening tool for drug screening purposes to identify possible substrates of human P-glycoprotein.

A new phenothiazine derivate is active against Clostridioides difficile and shows low cytotoxicity

The rapid evolution of antibiotic resistance in Clostridioides difficile and the consequent effects on prevention and treatment of C. difficile infections (CDIs) are matters of concern for public health. Thioridazine, a compound belonging to the phenothiazine group, has previous shown antimicrobial activity against C. difficile. The purpose of this present study was to investigate the potential of a novel phenothiazine derivative, JBC 1847, as an oral antimicrobial for treatment of intestinal pathogens and CDIs. The minimal inhibition concentration and the minimum bactericidal concentration of JBC 1847 against C. difficile ATCC 43255 were determined 4 μg/mL and high tolerance after oral administration in mice was observed (up to 100 mg/kg bodyweight). Pharmacokinetic modeling was conducted in silico using GastroPlus^TM, predicting low (< 10%) systemic uptake after oral exposure and corresponding low C_max in plasma. Impact on the intestinal bacterial composition after four days of treatment was determined by 16s rRNA MiSeq sequencing and revealed only minor impact on the microbiota in non-clinically affected mice, and there was no difference between colony-forming unit (CFU)/gram fecal material between JBC 1847 and placebo treated mice. The cytotoxicity of the compound was assessed in Caco-2 cell-line assays, in which indication of toxicity was not observed in concentrations up to seven times the minimal bactericidal concentration. In conclusion, the novel phenothiazine derivative demonstrated high antimicrobial activity against C. difficile, had low predicted gastrointestinal absorption, low intestinal (in vitro) cytotoxicity, and only induced minor changes of the healthy microbiota, altogether supporting that JBC 1847 could represent a novel antimicrobial candidate. The clinical importance hereof calls for future experimental studies in CDI models.

Efficacy of a novel antimicrobial hydrogel for eradication of Staphylococcus epidermidis, Staphylococcus aureus and Cutibacterium acnes from preformed biofilm and treatment performance in an in vivo MRSA wound model

BACKGROUND

Bacterial biofilm formation is a complicating factor in the antimicrobial treatment of bacterial infections.

OBJECTIVES

In this study, we assessed the impact of a novel hydrogel with the active antimicrobial compound JBC 1847 on eradication of preformed biofilms of Staphylococcus epidermidis, Cutibacterium acnes and MRSA in vitro, and evaluated the in vivo efficacy of MRSA wound treatment.

METHODS

Biofilms were exposed to JBC 1847 for 24 h and subsequently the treatments were neutralized and surviving biofilm-associated bacteria recovered and enumerated. The efficacy of the hydrogel on post-treatment load of MRSA was determined in a murine model of MRSA wound infection, and skin samples of the infected mice were examined histologically to evaluate the degree of healing.

RESULTS

A concentration-dependent eradication of biofilm-embedded bacteria by JBC 1847 was observed for all three pathogens, and the hydrogel caused a greater than four log reduction of cfu in all cases. In the mouse model, treatment with the hydrogel significantly reduced the cfu/mL of MRSA compared with treatment of MRSA-infected wounds with pure hydrogel. Histopathological analysis of the wounds showed that the JBC 1847 treatment group had a lower grade of inflammation, a higher mean score of re-epithelization and higher mean scores of parameters assessing the maturity of the newly formed epidermis, compared with both the fusidic acid 2% and vehicle treatment groups.

CONCLUSIONS

The novel hydrogel shows promising results as a candidate for future wound treatment, likely to be highly effective even in the case of biofilm-complicating infected wounds.

Gluten Degradation, Pharmacokinetics, Safety, and Tolerability of TAK-062, an Engineered Enzyme to Treat Celiac Disease

BACKGROUND AND AIMS

Celiac disease (CeD) is an immune-mediated disorder triggered by the ingestion of gluten. Despite adhering to a gluten-free diet (the only management option available to patients with CeD), many patients continue to experience symptoms and intestinal injury. Degradation of immunogenic fractions of gluten peptides in the stomach has been proposed as an approach to reduce toxicity of ingested gluten; however, no enzymes evaluated to date have demonstrated sufficient gluten degradation in complex meals. TAK-062 is a novel, computationally designed endopeptidase under development for the treatment of patients with CeD.

METHODS

Pharmacokinetics, safety, and tolerability of TAK-062 100-900 mg were evaluated in a phase I dose escalation study in healthy participants and patients with CeD. Gluten degradation by TAK-062 was evaluated under simulated gastric conditions in vitro and in healthy participants in the phase I study, with and without pretreatment with a proton pump inhibitor. Residual gluten (collected through gastric aspiration in the phase I study) was quantified using R5 and G12 monoclonal antibody enzyme-linked immunosorbent assays.

RESULTS

In vitro, TAK-062 degraded more than 99% of gluten (3 g and 9 g) within 10 minutes. In the phase I study, administration of TAK-062 was well tolerated and resulted in a median gluten degradation ranging from 97% to more than 99% in complex meals containing 1-6 g gluten at 20-65 minutes postdose.

CONCLUSIONS

TAK-062 is well tolerated and rapidly and effectively degrades large amounts of gluten, supporting the development of this novel enzyme as an oral therapeutic for patients with CeD. (ClinicalTrials.gov: NCT03701555, https://clinicaltrials.gov/ct2/show/NCT03701555.).

Human induced pluripotent stem cells (BIONi010-C) generate tight cell monolayers with blood-brain barrier traits and functional expression of large neutral amino acid transporter 1 (SLC7A5)

The barrier properties of the brain capillary endothelium, the blood-brain barrier (BBB) restricts uptake of most small and all large molecule drug compounds to the CNS. There is a need for predictive human in vitro models of the BBB to enable studies of brain drug delivery. Here, we investigated whether human induced pluripotent stem cell (hiPSC) line (BIONi010-C) could be differentiated to brain capillary endothelial- like cells (BCEC) and evaluated their potential use in drug delivery studies. BIONi010-C hIPSCs were differentiated according to established protocols. BCEC monolayers displayed transendothelial electrical resistance (TEER) values of 5,829±354 Ω∙cm², a P_app,_mannitol of 1.09±0.15 ∙ 10^-6 cm∙s^-1 and a P_app,diazepam of 85.7 ± 5.9 ∙ 10^-6 cm ∙s^-1. The P_diazepam/P_mannitol ratio of ~80, indicated a large dynamic passive permeability range. Monolayers maintained their integrity after medium exchange. Claudin-5, Occludin, Zonulae Occludens 1 and VE-Cadherin were expressed at the cell-cell contact zones. Efflux transporters were present at the mRNA level, but functional efflux of substrates was not detected. Transferrin-receptor (TFR), Low density lipoprotein receptor-related protein 1 (LRP1) and Basigin receptors were expressed at the mRNA-level. The presence and localization of TFR and LRP1 were verified at the protein level. A wide range of BBB-expressed solute carriers (SLC's) were detected at the mRNA level. The presence and localization of SLC transporters GLUT1 and LAT1 was verified at the protein level. Functional studies revealed transport of the LAT1 substrate [³H]-L-Leucine and the LRP1 substrate angiopep-2. In conclusion, we have demonstrated that BIONi010-C-derived BCEC monolayers exhibited, BBB properties including barrier tightness and integrity, a high dynamic range, expression of some of the BBB receptor and transporter expression, as well as functional transport of LAT1 and LRP1 substrates. This suggests that BIONi010-C-derived BCEC monolayers may be useful for studying the roles of LAT-1 and LRP1 in brain drug delivery.

Abstract 6340: Re-sensitization of irinotecan/SN38 resistant colorectal cancer cells by SCO-101

Introduction: Annually, more than 1 million people are diagnosed with Colorectal Cancer (CRC) and more than 500.000 die from CRC. Only three types of chemotherapy are currently being used worldwide to treat CRC patients: 5FU, oxaliplatin and irinotecan. However, chemotherapy resistance is present or develops in the majority of metastatic CRC patients. Resistance to anti-cancer drugs represents the main cause of cancer-related deaths. Thus, re-sensitization of chemotherapy resistant cancer cells constitutes a highly unmet medical need.

Materials and Methods: The drug, SCO-101, is an oral drug and has previously passed 4 Phase I clinical trials where it demonstrated excellent PK (T1/2=15 hours) and favourable safety profile. We used two pairs of parental (sensitive) and SN38-resistant (SN38 is the active metabilote of irinotecan) human colon cancer cell lines (HT29 and LoVo). Cell viability in vitro during 72h exposure to SCO-101 and/or SN38 was adressed by MTT assays. The level of the SN38 efflux transpoter, ABCG2/BCRP, was investigated in the presence or absence of SCO-101. Additionally, various flux assays were applied to investigate the effect of SCO-101 on ABCG2/BCRP activity. A kinase screen revealed that the kinase SRPK1 was inhibited by SCO-101 and the importance of SRPK1 activity in re-sensitization of SN38 resistant colon cancer cells was investigated by two different synthetic SRPK1 inhbitors.

Results: In parental HT29 and LoVo cells, SCO-101 and SN38 each had a dose-dependent effect on cell viability and no combinational effects were observed between the drugs. When exposing SN38-resistant cells to the combination of SCO-101 and SN38, a significant inhibitory effect on cell viability compared to either drug alone was observed, suggesting an additive or synergistic effect between these two drugs with SCO-101 re-sensitizing the resistant cells to SN38. Flux assays with ABCG2 /BCRP substrates clearly demonstrated that SCO-101 inhibited the activity of ABCG2 and protein analysis further demonstrated that SCO-101 causes degradation of ABCG2/BCRP. Cell viability assays with two different SRPK1 inhibitors demonstrated that this kinase is involved in re-sensitization to SN38.

Conclusion and future perspectives: These preclinical studies demonstrate that SCO-101 sensitizes SN38-resistant colon cancer cells to SN38 through two different mechanisms of actions e.g. inhibition of the SRPK1 kinase and degradation of the ABCG2/BCRP drug efflux pump. We are now preparing a clinical phase II study enrolling metastatic CRC patients, who have developed acquired resistance to irinotecan containing treatment. These patients will be re-exposed to the combination of irinotecan containing treatment and SCO-101. Primary end-points will be safety and objective response rate according to RECIST 1.1. Secondary end-points will be clinical benefit rate. The study has been approved by the Danish Medicines Agency. In conclusion, SCO-101 represents a unique drug with an innovative dual mechanism of action.

Citation Format: Jan Stenvang, Sophie Ambjørner, Khwajanezrabodin Sedighi, Peter Michael Vestlev, Lasse Saaby, Birger Brodin, Nils Brunner. Re-sensitization of irinotecan/SN38 resistant colorectal cancer cells by SCO-101 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6340.

Drug Delivery Strategies to Overcome the Blood-Brain Barrier (BBB)

The brain capillary endothelium serves both as an exchange site for gases and solutes between blood and brain and as a protective fence against neurotoxic compounds from the blood. While this "blood-brain barrier" (BBB) function protects the fragile environment in the brain, it also poses a tremendous challenge for the delivery of drug compounds to the brain parenchyma. Paracellular brain uptake of drug compounds is limited by the physical tightness of the endothelium, which is tightly sealed with junction complexes. Transcellular uptake of lipophilic drug compounds is limited by the activity of active efflux pumps in the luminal membrane. As a result, the majority of registered CNS drug compounds are small lipophilic compounds which are not efflux transporter substrates. Small molecule CNS drug development therefore focuses on identifying compounds with CNS target affinity and modifies these in order to optimize lipophilicity and decrease efflux pump interactions. Since efflux pump activity is limiting drug uptake, it has been investigated whether coadministration of drug compounds with efflux pump inhibitors could increase drug uptake. While the concept works to some extent, a lot of challenges have been encountered in terms of obtaining efficient inhibition while avoiding adverse effects.Some CNS drug compounds enter the brain via nutrient transport proteins, an example is the levodopa, a prodrug of Dopamine, which crosses the BBB via the large neutral amino acid transporter LAT1. While carrier-mediated transport of drug compounds may seem attractive, the development of drugs targeting transporters is very challenging, since the compounds should have a good fit to the binding site, while still maintaining their CNS target affinity.Receptor-mediated transport of drug compounds, especially biotherapeutics, conjugated to a receptor-binding ligand has shown some promise, although the amounts transported are rather low. This also holds true for drug-conjugation to cell-penetrating peptides. Due to the low uptake of biotherapeutics, barrier-breaching approaches such as mannitol injections and focused ultrasound have been employed with some success to patient groups with no other treatment options.

Dark chocolate as a stable carrier of microencapsulated Akkermansia muciniphila and Lactobacillus casei

The viability of probiotics is affected by several factors during manufacturing, storage and gastrointestinal tract passage. Protecting the probiotics from harmful conditions is particularly critical for oxygen sensitive species like Akkermansia muciniphila, a bacterium which recently has been proposed as a next-generation probiotic candidate. Previously, we have developed a protocol for microencapsulating A. muciniphila in a xanthan/gellan gum matrix. Here, we report the enhanced survival during storage and in vitro gastric passage of microencapsulated A. muciniphila embedded in dark chocolate. Lactobacillus casei, as a representative species of traditional probiotics, was included in order to compare its behavior with that of A. muciniphila. For A. muciniphila we observed a 0.63 and 0.87 log CFU g-1 reduction during 60 days storage at 4°C or 15°C, respectively. The viability of L. casei remained stable during the same period. During simulated gastric transit (pH 3), microencapsulated A. muciniphila embedded in chocolate showed 1.80 log CFU mL-1 better survival than naked cells, while for L. casei survival was improved with 0.8 log CFU mL-1. In a hedonic sensory test, dark chocolate containing microcapsules were not significantly different from two commercially available chocolates. The developed protocol constitutes a promising approach for A. muciniphila dosage.

SEDDS for intestinal absorption of insulin: Application of Caco-2 and Caco-2/HT29 co-culture monolayers and intra-jejunal instillation in rats

To face the challenges of oral delivery of peptide and protein (P/P) drugs, self-emulsifying drug delivery systems (SEDDSs) containing monoacyl phosphatidylcholine (MAPC), Labrasol (LAB) and medium-chain (MC) monoglycerides as permeation enhancers (PEs) were evaluated for their effect on intestinal absorption of insulin. In this study, insulin was complexed with phosphatidylcholine (SPC) to form an insulin-SPC complex (ins-SPC) with increased lipophilicity. The following three SEDDSs: MCT(MAPC) (MC triglycerides and MAPC included), MCT(RH40) (MC triglycerides and Kolliphor^® RH40 included) and LCT(MAPC) (long-chain triglycerides and MAPC included) were loading with ins-SPC (4% or 8% w/w of SPC). Three SEDDSs generated emulsions with droplet sizes between 50 and 470 nm and with zeta potentials between -5 to -25 mV in a simulated intestinal medium. Mucus-secreting Caco-2/HT29-MTX-E12 co-culture and Caco-2 monolayers were used as in vitro cell transport models to investigate insulin permeability. In comparison to insulin HBSS solution, MCT(MAPC) significantly increased the insulin permeability across co-culture and Caco-2 monolayers (2.0-2.5 × 10^-7 cm/s). In an intra-jejunal (i.j.) instillation model in rats, MCT(RH40) significantly decreased the rat blood glucose after 0.5 h by 17.0 ± 2.5% and for MCT(MAPC), it was 23.6 ± 10.6%. Furthermore, a lipase inhibitor orlistat was incorporated into MCT(MAPC) to evaluate the effect of lipid digestion on insulin absorption. Results indicated that the incorporation of orlistat did not significantly alter the in vivo insulin absorption. Overall, the SEDDS MCT(MAPC) composed of natural PEs (MAPC and MC glycerides) and synthetic PE (LAB) significantly increased the intestinal absorption of insulin upon i.j. instillation. Although it is not possible to conclude if a single PE is dominating the intestinal absorption of insulin, MCT(MAPC) seems to have the potential for oral insulin delivery.

Data demonstrating the challenges of determining the kinetic parameters of P-gp mediated transport of low-water soluble substrates

The presented data are related to the research article entitled “Characterization of the IPEC-J2 MDR1 (iP-gp) cell line as a tool for identification of P-gp substrates” by Ozgur et al. (2017) [1]. This data report describes the challenges of investigating the concentration-dependent transport of P-glycoprotein (P-gp) substrates with relatively low aqueous solubility. Thus, we provide solubility data on two prototypical P-gp substrates, digoxin and rhodamine 123, representing P-gp substrates with a relatively low- and high-aqueous solubility, respectively. We present a hypothetical Michaelis-Menten curve of the P-gp mediated transport of digoxin to demonstrate that the maximal donor concentration, which can be reached in the experimental transport buffer, is too low to yield transport data in the saturable range of the Michaelis-Menten relationship. Furthermore, we present data on the bidirectional transport of digoxin and rhodamine 123 across cell monolayers of the MDCK II MDR1 cell line and iP-pg cell line in the presence of the selective P-gp inhibitor, zosuquidar/LY335979.

Characterization of the IPEC-J2 MDR1 (iP-gp) cell line as a tool for identification of P-gp substrates

Recently, we transfected the porcine intestinal cell line IPEC-J2, with human P-glycoprotein (P-gp, ABCB1). The resulting cell line, iP-gp, has a high expression of functional human P-gp in the apical membrane, and a low expression of nonhuman ATP-binding cassette (ABC) transporters. The aim of the present work was to investigate the usability of iP-gp cell line for determining transepithelial transport kinetics of the prototypical P-gp substrates digoxin and rhodamine 123. The cell line generated tight monolayers after 16days of culture, reflected by high transepithelial electrical resistance values (TEER>15,000Ω·cm²), immunocytochemistry and low fluxes of the paracellular flux marker [¹⁴C]-mannitol. Monolayer integrity was not affected the common solvents dimethyl sulfoxide (DMSO), methanol and ethanol in concentrations up to 2% (v/v). Transepithelial fluxes of [³H]-labeled digoxin and rhodamine 123 were measured at varying donor concentrations, and kinetic parameters were estimated. K_m and V_max of P-gp mediated basolateral-to-apical (B-A) flux of rhodamine 123 were estimated to 332±124μM and 111±16pmol·cm^-2·min^-1 (n=3, total N=6), respectively. V_max and K_m of digoxin B-A flux could not be estimated due to the low aqueous solubility of digoxin. The half maximal inhibitory concentrations (IC₅₀) of the selective P-gp inhibitor, zosuquidar (LY-335979), were estimated to 0.05±0.01μM (n=3, total N=6) and 0.04±0.01μM (n=3, total N=6) in transport experiments with digoxin and rhodamine 123 as substrates, respectively. Bidirectional fluxes of digoxin and rhodamine 123 were measured in transfected Madin Darby canine kidney cells (MDCK II MDR1) and compared with the fluxes obtained with the iP-gp cell monolayers. Efflux ratios were highest in the iP-gp cells, due to a tighter paracellular pathway. In conclusion, both digoxin and rhodamine 123 could be used to obtain IC₅₀ values of inhibition, K_i values were only possible to obtain using rhodamine 123. The observed tightness, robustness towards solvents and the high efflux ratios confirmed that the iP-gp cell line may serve as a useful screening tool for investigations of substrate-P-gp interactions and modulation of P-gp function.

IPEC-J2 MDR1, a Novel High-Resistance Cell Line with Functional Expression of Human P-glycoprotein (ABCB1) for Drug Screening Studies

The P-glycoprotein (P-gp) efflux pump has been shown to affect drug distribution and absorption in various organs and to cause drug resistance in cancer therapy. The aim of this work was to develop a cell line to serve as a screening system for potential substrates of P-gp. This requires a cell line with high paracellular tightness, low expression of nonhuman ABC transporters, and high expression of functional human P-gp (ABCB1). The porcine intestinal epithelial cell line, IPEC-J2, was selected as a transfection host, due to its ability to form extremely high-resistance monolayers (>10,000 Ω·cm(2)) and its low endogenous expression of ABC-type efflux transporters. The IPEC-J2 cells were transfected with a plasmid that contained the sequence of the human MDR1 gene, which encodes P-gp, followed by a selection of successfully transfected cells with geneticin and puromycin. The resulting cell line, IPEC-J2 MDR1, retained its high transepithelilal resistance (>15,000 Ω·cm(2)), which translated into low permeability of the small hydrophilic tracer, mannitol (P < 10(-7) cm·s(-1)). The lipophilic compound, diazepam, displayed high permeability resulting in a dynamic range of 1500 (PDiazepam/Pmannitol) to separate high and low permeability compounds. Human P-gp was expressed predominantly in the apical membrane, as demonstrated by immunocytochemistry, Western blots, and a high efflux ratios (Pbasolateral-apical/Papical-basolateral) of known P-gp substrates. P-gp was demonstrated to be responsible for the efflux transport by substrate profiling, combined with application of P-gp and BCRP inhibitors. Furthermore, the compounds atenolol, citalopram, and mitoxantrone were identified as P-gp substrates. Functional P-gp expression was shown to be stable through at least 10 cell passages. In conclusion, the IPEC-J2 MDR1 cell line displays high paracellular tightness combined with high expression of human P-gp and low expression of porcine ABC transporters, and it may serve as a useful tool in drug development studies.

The putative P-gp inhibitor telmisartan does not affect the transcellular permeability and cellular uptake of the calcium channel antagonist verapamil in the P-glycoprotein expressing cell line MDCK II MDR1

Verapamil is used in high doses for the treatment of cluster headache. Verapamil has been described as a P-glycoprotein (P-gp, ABCB1) substrate. We wished to evaluate in vitro whether co administration of a P-gp inhibitor with verapamil could be a feasible strategy for increasing CNS uptake of verapamil. Fluxes of radiolabelled verapamil across MDCK II MDR1 monolayers were measured in the absence and presence of the putative P-gp inhibitor telmisartan (a clinically approved drug compound). Verapamil displayed a vectorial basolateral-to-apical transepithelial efflux across the MDCK II MDR1 monolayers with a permeability of 5.7 × 10(-5) cm sec(-1) compared to an apical to basolateral permeability of 1.3 × 10(-5) cm sec(-1). The efflux could be inhibited with the P-gp inhibitor zosuquidar. Zosuquidar (0.4 μmol/L) reduced the efflux ratio (PB-A/PA-B) for verapamil 4.6-1.6. The presence of telmisartan, however, only caused a slight reduction in P-gp-mediated verapamil transport to an efflux ratio of 3.4. Overall, the results of the present in vitro approach indicate, that clinical use of telmisartan as a P-gp inhibitor may not be an effective strategy for increasing brain uptake of verapamil by co-administration with telmisartan.

Bioavailability of cinnarizine in dogs: effect of SNEDDS loading level and correlation with cinnarizine solubilization during in vitro lipolysis

PURPOSE

To investigate the effect of increasing the loading level of the poorly soluble drug cinnarizine in a self-nanoemulsifying drug delivery system (SNEDDS) both in vitro and in vivo.

METHODS

A fixed dose of cinnarizine was administered orally to dogs in solution in different amounts of SNEDDS vehicle. Furthermore, the SNEDDSs were characterised using the dynamic in vitro lipolysis model.

RESULTS

Statistical differences in bioavailability were not obtained between the different amounts of SNEDDS vehicle, in spite of differences in the tendency of cinnarizine to precipitate during in vitro lipolysis of the treatments. Use of the SNEDDS concept decreased the variation in cinnarizine exposure observed between dogs as compared to administering cinnarizine in an aqueous suspension.

CONCLUSIONS

Optimization of SNEDDSs towards keeping the drug compound in solution upon in vitro lipolysis of the SNEDDSs may not be as important as previously suggested.

Considerations regarding use of solvents in in vitro cell based assays

Cell culture systems are widely used for the investigation of in vitro immunomodulatory effects of medicines and natural products. Since many pharmacological relevant compounds are water-insoluble, solvents are frequently used in cell based assays. Although many reports describe the cellular effects of solvents at high concentrations, only a few relate the effects of solvents used at low concentrations. In this report we investigate the interference of three commonly used solvents: Dimethyl sulfoxide (DMSO), ethanol and β-cyclodextrin with five different cell culture systems. The effects of the solvents are investigated in relation to the cellular production of interleukin (IL)-6 or reactive oxygen species (ROS) after lipopolysaccharide (LPS) stimulation. We show that DMSO above 1 % reduces readout parameters in all cell types but more interestingly the 0.25 and 0.5 % solutions induce inhibitory effects in some cell types and stimulatory effects in others. We also found that LPS induced ROS production was more affected than the IL-6 production in the presence of ethanol. Finally we showed that β-cyclodextrin at the investigated concentrations did not have any effect on the LPS induced IL-6 production and only minor effects on the ROS production. We conclude that the effects induced by solvents even at low concentrations are highly relevant for the interpretation of immunomodulatory effects evaluated in cell assays. Furthermore, these results show the importance of keeping solvent concentrations constant in serial dilution of any compound investigated in cell based assays.

Triterpene acids from rose hip powder inhibit self-antigen- and LPS-induced cytokine production and CD4⁺ T-cell proliferation in human mononuclear cell cultures

A triterpene acid mixture consisting of oleanolic, ursolic and betulinic acid isolated from a standardized rose hip powder (Rosa canina L.) has been shown to inhibit interleukin (IL)-6 release from Mono Mac 6 cells. The present study examined the effects of the triterpene acid mixture on the cytokine production and proliferation of CD4⁺ T cells and CD19⁺ B cells induced by a self-antigen, human thyroglobulin and by lipopolysaccharide in cultures of normal mononuclear cells. The triterpene acid mixture inhibited the production of tumor necrosis factor-α and IL-6 with estimated IC₅₀ values in the range 35-56 µg/mL, the Th1 cytokines interferon-γ and IL-2 (IC₅₀ values 10-20 µg/mL) and the antiinflammatory cytokine IL-10 (IC₅₀ values 18-21 µg/mL). Moreover, the mixture also inhibited CD4⁺ T-cell and CD19⁺ B-cell proliferation (IC₅₀ value 22 and 12 µg/mL, respectively). Together, these data demonstrate that oleanolic, ursolic and betulinic acid are active immunomodulatory constituents of the standardized rose hip powder. However, since the estimated IC₅₀ values are in the µg/mL range, it is questionable whether the content of the triterpene acids in the standardized rose hip powder, alone, can explain the reported clinical effects.

Flavonoids and the CNS

Flavonoids are present in almost all terrestrial plants, where they provide UV-protection and colour. Flavonoids have a fused ring system consisting of an aromatic ring and a benzopyran ring with a phenyl substituent. The flavonoids can be divided into several classes depending on their structure. Flavonoids are present in food and medicinal plants and are thus consumed by humans. They are found in plants as glycosides. Before oral absorption, flavonoids undergo deglycosylation either by lactase phloridzin hydrolase or cytosolic β-glucocidase. The absorbed aglycone is then conjugated by methylation, sulphatation or glucuronidation. Both the aglycones and the conjugates can pass the blood-brain barrier. In the CNS several flavones bind to the benzodiazepine site on the GABA_A-receptor resulting in sedation, anxiolytic or anti-convulsive effects. Flavonoids of several classes are inhibitors of monoamine oxidase A or B, thereby working as anti-depressants or to improve the conditions of Parkinson’s patients. Flavanols, flavanones and anthocyanidins have protective effects preventing inflammatory processes leading to nerve injury. Flavonoids seem capable of influencing health and mood.

Isolation of immunomodulatory triterpene acids from a standardized rose hip powder (Rosa canina L.)

A previously published systematic review and a metaanalysis have concluded that the consumption of standardized rose hip powder (Rosa canina L.) can reduce pain in osteoarthritis patients. Synovial inflammation has been suggested to play an important role in the pathogenesis of osteoarthritis and mainly to involve infiltration of the synovial membrane by macrophages. Therefore, the immunomodulatory effect of standardized rose hip powder of Rosa canina L. was investigated and active principles isolated using the Mono Mac 6 cell line as a model for human macrophages. Treatment of Mono Mac 6 cells with the residue of a crude dichloromethane extract of rose hip powder significantly and concentration dependently inhibited the lipopolysaccharide induced interleukin-6 release. Through bioassay-guided fractionation the immunomodulatory effect of the dichloromethane extract was correlated to a mixture of three triterpene acids; oleanolic acid, betulinic acid and ursolic acid (IC(50) 21 ± 6 µm). Further studies revealed that only oleanolic acid and ursolic acid, but not betulinic acid, could inhibit the lipopolysaccharide induced interleukin-6 release from Mono Mac 6 cells when tested separately. Combination of either oleanolic acid or ursolic acid with betulinic acid enhanced the immunomodulatory effect of the two triterpene acids.

Short communication: Influence of pasteurization on the active compounds in medicinal plants to be used in dairy products

Interest from the dairy industry in adding herbal drugs to milk and yogurt products raises the question of whether these plant materials can be pasteurized. Root material of Rhodiola rosea, Eleutherococcus senticosus, and Panax ginseng, all plants with adaptogenic activities, was pasteurized. The content of active compounds in the root material before and after pasteurization was quantified by HPLC analysis. The results show that the eleutherosides in E. senticosus, and to an extent the ginsenosides from P. ginseng, could withstand pasteurization, whereas salidroside and rosavin from R. rosea did not survive pasteurization. Thus, R. rosea is not suitable for products requiring pasteurization.

[Drug-drug interactions in intensive care patients]

INTRODUCTION

The purpose of this study was to investigate the frequency of potential drug-drug interactions (DDIs) within the first 24 hours of admission to an intensive care unit, and to determine which drugs were involved in potential DDIs along with the clinical relevance of the identified DDIs.

METHODS

Drug data from all intensive care patients (n = 102) admitted during a three-month period in the spring 2007 were investigated. Potential DDIs were evaluated using the drug interaction system of Micromedex.

RESULTS

Four patients were excluded because their treatment only included one drug. A total of 98 patients were treated with an average of ten drugs per patient. Among the enrolled patients, we found 242 potential DDIs, corresponding to an average of 2.5 DDIs per patient. The drugs most frequently involved in potential DDIs included antithrombotic drugs, opioids, loop diuretics, ACE inhibitors, beta blockers, NSAIDs, corticosteroids, quinolon antibiotics, cardiac glycosides, thiazide diuretics, -anaesthetics, antidepressants, anticonvulsants and sedatives.

DISCUSSION

The number of DDIs per patient found in this study is high compared with the results of a recent Norwegian study. The majority of the identified DDIs were normal combinations of drugs, which are managed through monitoring of the patient and discontinuing of the offending drug if necessary. It is therefore important to revise the patient's medication daily.

CONCLUSION

A total of 71% of the 98 enrolled patients were exposed to one or more potential DDIs. We found an average of 2.5 potential DDIs per patient. Antithrombotic drugs, opioids and loop diuretics were most frequently involved in potential DDIs. The clinical relevance varied because the majority of the identified potential DDIs were normal drug combinations.

MAO-A inhibitory activity of quercetin from Calluna vulgaris (L.) Hull

AIM OF THE STUDY

This study investigated MAO-A inhibitory activity of methanol extract of Calluna vulgaris (L.) Hull., which traditionally has been used as a nerve calming remedy.

MATERIALS AND METHODS

A methanolic extract of Calluna vulgaris was partitioned against heptane, ethyl acetate and water. The three fractions were tested in a photometric peroxidase linked MAO-A bioassay. The ethyl acetate phase showed the highest MAO-A inhibitory activity. Quercetin was isolated by VLC through bioassay-guided fractionation and purified by re-crystallisation. The structure was elucidated by LC-MS and (1)H NMR.

RESULTS

The IC(50)-value for MAO-A inhibition by quercetin was 18+/-0.2 microM in an assay where the IC(50)-value for MAO-A inhibition by clorgylin was 0.2+/-0.02 microM.

CONCLUSION

The content of quercetin in Calluna vulgaris might explain the reported nerve calming effect of the plant.