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Dose-response analysis of nanomaterial toxicity

Tijdschriftbijdrage - Tijdschriftabstract Conferentiebijdrage

dexamethasone therapy, we apply physiologically-based pharmaco-kinetic (PBPK) modelling to predict foetal exposure after maternal dosing. Methods: To characterize the placental handling of dexametha-sone ex vivo, we performed dual-side perfused isolated human cotyledon experiments (n = 3) with term placenta in closed-closed setting. The tissue was perfused for 3 hours with 70 ng/mL dexamethasone in Krebs-Henseleit buffer. Next, intrinsic unbound placental transfer values were derived from the perfusion data using a physiologically-based semi-mechanistic placenta (PBMP) model in Matlab. Values were used for parameterization of Simcyp's pregnancy-PBPK (p-PBPK) model to predict maternal and foetal exposure. In addition, to evaluate whether placental exposure to the drug may result in adverse effects on placental syncytiotrophoblasts, a toxicity screening exposing BeWo cells to dexamethasone concentrations in a range of 5-25.000 nM for 24 hours was executed. Results: Perfusion experiments showed that dexamethasone extensively crosses the placenta. The PBMP model adequately described the perfusion data. The intrinsic unbound transfer values derived, were estimated to be 1033.5 mL/min and 15.2 mL/min for the maternal placental uptake and efflux, and 1311.1 mL/min and 10.7 mL/ min for foetal placental uptake and efflux, respectively. For an intramuscular dose of 8 mg at 28 weeks of gestation, whole body p-PBPK modelling predicted a C max and AUC 0−∞ of 46.09 ng/mL and 230.46 ng/ml*h in maternal plasma and a C max and AUC 0−∞ of 18.60 ng/mL and 100.25 ng/ml*h in the umbilical vein, respectively. Umbilical vein plasma concentrations derived from literature (range 5.5-23.7 ng/mL) are in accordance with the estimated C max concentration. None of the drug concentrations studied affected placental cell viability or progesterone production in BeWo cells. Conclusion: Ex vivo placenta perfusion in combination with p-PBPK modelling is a relevant approach for foetal exposure predictions. Outcomes can be used in re-evaluation of current dosing regimens of dexamethasone during pregnancy. It is expected that this approach can be used to predict foetal exposure to other pharmaceutical drugs as well, even in absence of umbilical vein concentrations of a drug. As nanomaterials are increasingly used in many different products, it becomes important to know their potential toxicity. In the risk assessment of nanomaterials, in vitro-in vivo extrapolation (IVIVE) techniques are interesting to be explored since they have advantages of maximizing the use of in vitro studies, and reducing the financial and time costs, especially when high numbers of nanomaterials are to be analyzed. The H2020 NanoInformaTIX project is a research project that partly focuses on the study of nanomaterial toxicity, with our goal being, implementing IVIVE methods for use in a strategy for risk assessment of nanomaterials. The initial step of our research includes building a software program (the R package NMTox) to explore the data gathered through the project and to perform preliminary analysis on the dose-response relationship of nanomaterial toxicity. Methods available in this package, such as the Likelihood ratio test, are used to test for the monotonic trend in dose-response relationships, and thus to screen for potential significant dose-response relationships of nanomaterials toxicity, that can be analyzed further. To identify the toxic concentrations, dose-response models are fitted on the subsets of data with a significant trend. The risk assessment strategy will involve applying IVIVE methods described in the literature and will use the estimated in vitro toxic concentration as the basis for the risk calculation. The current stage of our research is focusing on PBPK models to estimate in vivo toxic doses of nanomaterials and to aid the risk assessment strategy. The feasibility of applying this strategy is currently being investigated. We will illustrate this approach using data available in the NanoInformaTIX database and in the literature. Most studies assess the possible adverse effects of exposure to airborne nanomaterials (NMs) using submerged culture systems; however, air-liquid interface (ALI) exposure systems are far better suited for the assessment of in vitro pulmonary effects of NMs as they are more representative of the in vivo respiratory system. Although ALI exposure is preferred over submerged conditions, it is not known how toxicity, uptake and intracellular fate of NMs in cells may be influenced when ALI is compared with submerged exposure conditions. The aim of this study was to compare the distribution, toxicity, and cellular uptake of 14 nm citrate stabilised gold nanoparticles (AuNPs) exposed to human alveolar basal epithelial (A549) cells at the ALI (0.13, 0.21 and 0.443 μg/cm 2), using the VITROCELL ® Cloud 12 in vitro exposure system, to submerged conditions (10, 20, 40 μg/cm 2 , a 10-fold increase to account for sedimentation and diffusion). The toxicity of A549 cells was monitored using the lactate dehydrogenase (LDH) assay as this assay has previously shown to not be affected by interference of AuNPs. The distribution and intracellular uptake were assessed using conventional inverted microscopy and the CytoViva 3D Enhanced Darkfield Imaging System. The AuNPs were shown to be relatively non-toxic under both ALI and submerged conditions, however the cells showed increased sensitivity at the ALI. The distribution and intracellular uptake of the AuNPs were found to be more uniformly distributed, over the exposure area of the transwell insert, at the ALI whereas submerged conditions resulted in agglomerated NPs, outside cells as well as intracellularly. The use of the CytoViva 3D system has shown to be beneficial when assessing uptake of non-labelled NPs within a three-dimensional space. S198 Abstracts / Toxicology Letters 368S1 (2022) S84-S283
Tijdschrift: Toxicology letters
ISSN: 0378-4274
Volume: 368
Pagina's: S198
Jaar van publicatie:2022
Toegankelijkheid:Closed