The Growing Importance of Three-Dimensional Models and Microphysiological Systems in the Assessment of Mycotoxin Toxicity

Low concentrations of complex mixtures of pesticides and metabolites are toxic to common Carp brain cells (Cyprinus carpio carpio)

Pesticide use increases annually, and Brazil is the world's largest consumer. However, unlike the European Union (EU), there is no established limit value for pesticide mixtures in drinking water, and therefore the concentration of pesticides can reach 3354 times the EU limit. Thus, determining the risk of exposure to pesticide mixtures and their main metabolites is challenging and requires the use of alternative methods. In the present study, the Common Carp Brain (CCB) cell line was used to evaluate the in vitro toxicity of relevant pesticide mixtures (glyphosate, 2,4-D, atrazine, and mancozeb) and their main metabolites after 72 h of exposure. The tested concentrations were based on the Acceptable Daily Intake (ADI) defined by Brazilian legislation. The results showed that cells exposed to lower concentrations of the pesticide mixtures and the pesticide + metabolite mixtures were affected by a decrease in cell confluence, resazurin metabolism, and wound healing capacity. The IBR index showed that lower concentrations had more severe effects, suggesting the absence of safe concentrations of these pesticide and metabolite mixtures for the CCB cell line within the tested concentration range. These findings raise concerns about the effects of exposure to these substances on animal and human health.

Environmental mycotoxins: A potential etiological factor for neurodegenerative diseases?

Mycotoxins are potential environmental risk factors for neurodegenerative diseases. These toxins penetrate the central nervous system via a compromised blood-brain barrier, which may cause oxidative stress and neuroinflammation, these can also contribute to amyloid-beta (Aβ) plaque accumulation, Tau protein hyperphosphorylation, and neurofibrillary tangle formation. Mycotoxins also activate microglia, cause neuronal apoptosis, and disrupt central nervous system function. This study examines the evidence linking mycotoxin exposure to neurodegenerative disorders like Alzheimer's and Parkinson's diseases. We explore mechanisms such as oxidative stress, mitochondrial dysfunction, blood-brain barrier disruption, neuroinflammation, and direct neurotoxic effects. Epidemiological studies show regional variations in mycotoxin prevalence and corresponding neurodegenerative disease incidences, supporting this association. We also review current approaches to mitigate mycotoxin exposure and discuss the challenges and opportunities in developing strategies to prevent or slow neurodegenerative disease progression. This work highlights the need for increased awareness and research on mycotoxins as modifiable risk factors in neurological health.

An overview of immunotoxicity in drug discovery and development

The immune system is one of the common targets of drugs' toxicity (Immunotoxicity) and/or efficacy (Immunotherapy). Immunotoxicity leads to adverse effects on human health, which raises serious concerns for the regulatory agencies. Currently, immunotoxicity assessment is conducted using different in vitro and in vivo assays. In silico and in vitro human cell-based immunotoxicity assays should also be explored for screening purposes as these are time and cost effective as well as for ethical reasons. For in vivo studies, tier 1-3 assessments (Tier 1: hematology, serum globulin levels, lymphoid organ's weight and histopathology; Tier 2: immunophenotyping, TDAR and cell mediated immunity; and Tier 3: host resistance) should be used. These non-clinical in vivo assessments are useful to select immunological endpoints for clinical trials as well as for precautionary labeling. As per regulatory guidelines, adverse immunogenicity information of drug should be included in product's labeling to make health care practitioner aware of safety concerns before prescribing medicines and patient management (USFDA, 2022a, 2022b). This review mainly focuses on the importance of immunotoxicity assessment during drug discovery and development.

Polo-like kinase 1 inhibition modulates urinary tract smooth muscle contraction and bladder cell transcriptional programs

The serine/threonine kinase polo-like kinase 1 (PLK1) is a master regulator of cell proliferation and contraction, but its physiological role in the lower urinary tract is unknown. We utilized transcriptomic programs of human bladder smooth muscle cells (hBSMCs), 3D bladder spheroid viability assays, and human ureterovesical junction contractility measurements to elucidate the impacts of PLK1 inhibition. This work reveals PLK1 reduction with the selective inhibitor TAK-960 (500 nM) suppresses high K+-evoked contractions of human urinary smooth muscle ex vivo while decreasing urothelial cell viability. Transcriptomic analysis of hBSMCs treated with TAK-960 shows modulation of cell cycle and contraction pathways, specifically through altered expression of Cys2/His2-type zinc finger transcription factors. In bladder spheroids, PLK1 inhibition also suppresses smooth muscle contraction protein filamin. Taken together, these findings establish PLK1 is a critical governor of urinary smooth muscle contraction and urothelial proliferation with implications for lower urinary tract disorders. Targeting PLK1 pharmacologically may therefore offer therapeutic potential to ameliorate hypercontractility and aberrant growth. Further elucidation of PLK1 signaling networks promises new insights into pathogenesis and much needed treatment advances for debilitating urinary symptoms.

Development of an Easy-To-Use Microfluidic System to Assess Dynamic Exposure to Mycotoxins in 3D Culture Models: Evaluation of Ochratoxin A and Patulin Cytotoxicity

Mycotoxins are among the most concerning natural toxic food contaminants. Over the years, significant efforts have been made to characterize the risk associated with their exposure. However, assessing their toxicity has so far been elusive due to the lack of adequate models that closely mimic the physiological conditions of human cells in vivo. Here, we present the SpheroFlow Device (SFD), an efficient microfluidic platform designed, manufactured, and validated to evaluate mycotoxin-induced cytotoxicity under dynamic and continuous exposure in 3D culture settings. In the present study, we integrated human neuroblastoma SH-SY5Y spheroids into the SFD to assess the acute toxicity induced by the mycotoxins ochratoxin A (OTA) and patulin (PAT). The developed system enabled qualitative and quantitative measurements of concentration-response relationships and provided accurate control over the culture microenvironment. Our findings show that by enhancing 3D culture model by applying dynamic flow, SH-SY5Y spheroids exhibited different sensitivities to OTA and PAT compared to conventional static SH-SY5Y spheroids, confirming the critical role of culture models in mycotoxin toxicity assessment. This is the first study assessing the neurotoxicity of OTA and PAT on 3D neuroblastoma spheroids considering the contribution of fluid flow.

Integrated Approach to Cyclopiazonic Acid Cytotoxicity Using In Vitro (2D and 3D Models) and In Silico Methods

Cyclopiazonic acid (CPA) is an indole-tetramic acid neurotoxin produced by Aspergillus and Penicillium genera present mainly in fruit, cereals and nuts. This study compares the cytotoxicity produced by CPA after 24, 48 and 72 h of exposure using both monolayers and 3D spheroids in human neuroblastoma SH-SY5Y cells. Furthermore, CPA toxicokinetics was evaluated using in silico models. Cytotoxicity increased dose- and time-dependently, as shown by the MTT assay. The lowest CPA IC50 values were found in the monolayer study compared to the 3D spheroids at all exposure times (24 h: 864.01 vs. 1132; 48 h: 437 vs. 1069; 72 h: 392 vs. 567 nM). The CPA exposure on SH-SY5Y spheroid organization and morphology was also studied. Morphological changes, including spheroid disaggregation, were observed after mycotoxin exposure. The in silico methods, SwissADME and admetSAR, were used for short and full ADMEt profiles of CPA. The ADMEt predictive profile shows high gastrointestinal absorption and ability to penetrate the blood-brain barrier. Including in silico studies emphasizes the comprehensive approach to understanding mycotoxin toxicity and risk assessment. By combining in vitro 3D spheroid models with computational simulations, this study aims to provide a holistic perspective on the effects of CPA, enhancing the accuracy and relevance of our findings.

Cytotoxic effects induced by combined exposure to the mycotoxins sterigmatocystin, ochratoxin A and patulin on human tumour and healthy 3D spheroids

Humans are exposed to complex mixtures of mycotoxins through diet. Despite the serious threat they pose, mycotoxin risk assessment often overlooks co-exposure. With the aim of filling this gap, the present study investigates the combined cytotoxicity of sterigmatocystin (STE), ochratoxin A (OTA) and patulin (PAT) in human tumour Neuroblastoma and healthy Mesenchymal Stem Cells three-dimensional (3D) spheroids. The range of concentrations tested (1.56-50 μM for STE, 0.78-25 μM for OTA and 0.15-5 μM for PAT) was selected considering the IC50 values obtained in previous studies and the estimated dietary exposure of consumers. To ensure appropriate experimental conditions, assessments for single mycotoxins and their combinations were conducted simultaneously. The nature of the toxicological interactions among the mycotoxins was then defined using the isobologram analysis. Our results demonstrated increased cytotoxicity in mycotoxin mixtures compared to individual exposure, with abundance of synergistic interactions. These findings highlight that the co-occurrence of STE, OTA and PAT in food may increase their individual toxic effects and should not be underestimated. Moreover, the use of advanced culture models increased the reliability and physiological relevance of our results which can serve as a groundwork for formulating standardized regulatory approaches towards mycotoxin mixtures in food and feed.

Label-free live characterization of mesenchymal stem cell spheroids by biophysical properties measurement

Three-dimensional (3D) cell culture has become a consolidated method in the stem cell field, where mesenchymal stromal stem cells (MSCs) can be used to generate in vitro spheroid aggregates called MSC-Spheroids (MSph). MSph is a floating cluster of stem cells similar to those in literature are known as bone marrow-derived "mesenspheres". Even though MSC properties are shared by MSph, depending on the cell type and their tissue source, the morphology and degree of compaction of the MSph can be variable, creating limitations in such a cell model. Thus, during culture, a variation in stem cell functionality and viability, in addition to the suitability for comparing MSph in some experimental protocols, can be affected by spheroid biophysical intrinsic properties like mass density. To investigate this limitation and provide a new method for researchers, MSph of seven different tissue sources were compared by combining mass density, weight, and size evaluations with viability assays for ATP measurement. MSph cultured in traditional static conditions showed decreased in viability over the days of culture, while mass density exhibited different trends among cell types. Additionally, treatment of MSph with a non-toxic concentration of a natural compound cell regulator, such as plumbagin, altered the mass density of a selected cell type, thereby confirming the efficacy of the biophysical approach in monitoring MSph variability post-treatment. The results encourage using MSph in the early days of culture after their formation to ensure viability and likely retention of the stem cell phenotype.

From Pipeline to Plant Protection Products: Using New Approach Methodologies (NAMs) in Agrochemical Safety Assessment

The human population will be approximately 9.7 billion by 2050, and food security has been identified as one of the key issues facing the global population. Agrochemicals are an important tool available to farmers that enable high crop yields and continued access to healthy foods, but the average new agrochemical active ingredient takes more than ten years, 350 million dollars, and 20,000 animals to develop and register. The time, monetary, and animal costs incentivize the use of New Approach Methodologies (NAMs) in early-stage screening to prioritize chemical candidates. This review outlines NAMs that are currently available or can be adapted for use in early-stage screening agrochemical programs. It covers new in vitro screens that are on the horizon in key areas of regulatory concern. Overall, early-stage screening with NAMs enables the prioritization of development for agrochemicals without human and environmental health concerns through a more directed, agile, and iterative development program before animal-based regulatory testing is even considered.

Comparative Study of Spheroids (3D) and Monolayer Cultures (2D) for the In Vitro Assessment of Cytotoxicity Induced by the Mycotoxins Sterigmatocystin, Ochratoxin A and Patulin

Mycotoxins are secondary metabolites produced by filamentous fungi associated with a variety of acute and chronic foodborne diseases. Current toxicology studies mainly rely on monolayer cell cultures and animal models, which are undeniably affected by several limitations. To bridge the gap between the current in vitro toxicology approach and the in vivo predictability of the data, we here investigated the cytotoxic effects induced by the mycotoxins sterigmatocystin (STE), ochratoxin A (OTA) and patulin (PAT) on different 2D and 3D cell cultures. We focused on human tumours (neuroblastoma SH-SY5Y cells and epithelial breast cancer MDA-MB-213 cells) and healthy cells (bone marrow-derived mesenchymal stem cells, BM-MSC, and umbilical vein endothelial cells, HUVECs). The cytotoxicity of STE, OTA, and PAT was determined after 24, 48 and 72 h of exposure using an ATP assay in both culture models. Three-dimensional spheroids' morphology was also analysed using the MATLAB-based open source software AnaSP 1.4 version. Our results highlight how each cell line and different culture models showed specific sensitivities, reinforcing the importance of using more complex models for toxicology studies and a multiple cell line approach for an improved and more comprehensive risk assessment.