Investigating the effects of differently produced synthetic amorphous silica (E 551) on the integrity and functionality of the human intestinal barrier using an advanced in vitro co-culture model

Abstract

E 551, also known as synthetic amorphous silica (SAS), is the second most produced food additive. However, according to the re-evaluation of E 551 by the European Food Safety Authority (EFSA) in 2018, the amount of available data on the oral toxicity of food grade E 551 is still insufficient for reliable risk assessment. To close this gap, this study aimed to investigate six food-grade SAS with distinct physicochemical properties on their interaction with the intestinal barrier using advanced in vitro intestinal co-cultures and to identify potential structure–activity relationships. A mucus-secreting Caco-2/HT-29/Raji co-culture model was treated with up to 50 µg/ml SAS for 48 h, which represents a dose range relevant to dietary exposure. No effects on cell viability, barrier integrity, microvilli function or the release of inflammatory cytokine were detected after acute exposure. Slight biological responses were observed for few SAS materials on iron uptake and gene expression levels of mucin 1 and G-protein coupled receptor 120 (GPR120). There was no clear correlation between SAS properties (single or combined) and the observed biological responses. Overall, this study provides novel insights into the short-term impact of food-relevant SAS with distinct characteristics on the intestinal epithelium including a range of intestine-specific functional endpoints. In addition, it highlights the importance of using advanced intestinal co-cultures embracing relevant cell types as well as a protective mucus barrier to achieve a comprehensive understanding of the biological response of food additives at the intestinal barrier in vitro.

Hazard Assessment of Abraded Thermoplastic Composites Reinforced with Reduced Graphene Oxide

“…It should be emphasized that no previous studies have analyzed possible alterations in the lipid absorption function of the intestinal barrier after GRM or other carbon-based material exposure. Interestingly, a previous study using synthetic amorphous silica did not observe any decline in the lipid uptake in a triple intestinal culture (Caco-2/HT-29/Raji co-culture) after 48 h of exposure (Hempt et al, 2020).…”

“…To investigate the potential effects of rGO and abraded PA6/PA6-rGO particles on lipid uptake, differentiated Caco-2 cells on 12-well inserts were exposed with different concentrations of each tested material (5-40 μg/mL) for 24 h and 48 h. Cell cultures treated with 50 µg/ mL of the fatty acid synthase inhibitor C75 for 24 h were used as a positive control. Lipid uptake was measured as described in previous work (Hempt et al, 2020). Briefly, after material exposures, the cultures were incubated for 10 min with 20 µM BODIPY™ 500/510 C1, C12 (Thermo Fischer, D3823) in 0.1% BSA, according to the manufacturer's instructions.…”

Genome-Wide DNA Methylation Alterations and Potential Risk Induced by Subacute and Subchronic Exposure to Food-Grade Nanosilica in Mice

“…Thus, to comprehend the genome-wide variations in DNA methylation induced by E 551, whole-genome bisulfite sequencing was performed on mice-exposed to E 551. E 551 is derived from thermal or wet manufacturing processes that result in different forms (fumed silica, precipitated silica, and silica gel); the different characteristics of various forms may affect their biological effects. , Therefore, two types of nanosized food-grade SAS produced by different manufacturing processes were chosen in this study. One of them was a fumed SAS (Aerosil 200F, A200F for short; thermal process silica), and the other was a precipitated SAS (S200; wet process silica).…”

In vitro-based human toxicity effect factors: challenges and opportunities for nanomaterial impact assessment

“…63 While submerged mono-cultures can be considered quite rudimentary systems, co-cultures, where different cell lines are cultured together to represent the complexity of cell-cell interactions, more realistically respond to nanomaterial exposure. [63][64][65][66] Depending on the case, additional factors have to be considered and integrated in the in vitro system to mimic physiological conditions. Cells exposed to a flow (e.g.…”