Acute and Sub-Chronic Effects of Microplastics (3 and 10 µm) on the Human Intestinal Cells HT-29.

Giuseppe De Marco,Maria Maisano,Alessio Facciolà,Giuseppa Visalli,Angela Di Pietro,Marianna Pruiti Ciarello

doi:10.3390/ijerph18115833

Abstract

Due to ingestion of contaminated foods, the human gastrointestinal tract is the most likely site of exposure to microplastics (MPs) with gut barrier dysfunction and intestinal inflammation. Aimed to assess the effects induced by MPs with different granulometry (polystyrene (PS) 3 and 10 µm), we performed an in vitro study by using the human intestinal cell line HT29. As a novelty, we assessed the sub-chronic exposure extending the treatment up to 48 days simulating the in vivo situation. In the range of 100–1600 particles mL−1, both the PS suspensions had moderate cytotoxicity after 24 h with percentages of mortality between 6.7 and 21.6 for the 10 µm and 6.1 and 29.6 for the 3 µm PS. Microscopic observation highlighted a more pronounced lysosomal membrane permeabilization in HT29 exposed to PS 3µm. Reactive oxygen species production was higher in cells exposed to PS 10 µm, but sub-chronic exposure highlighted the ability of the cells to partially neutralize this effect. Comet-assay confirmed the temporary oxidative damage that was PS-induced. Overall, considering the very fast turnover of intestinal cells, the increase in cell mortality, equal to 25% and 11% for 3 and 10 µm PS-MPs for each time point, could trigger intestinal disorders due to prolonged exposure.

Highlights

To assess the acute effects of exposure to 3 and 10 μm polystyrene microplastics (PS-MPs), we initially evaluated cytotoxicity in our cell model using the MTT test
The results obtained in our study show moderate acute effects and, to a lesser extent, subchronic effects of PS-MP exposure
Even if the differences in sizes of the examined PS-MPs were relatively small, the uptake occurred by different pathways, causing damage to the acid compartment and a higher increase of reactive oxygen species (ROS) in 3 and 10 μm particles respectively

Summary

Introduction

Microplastics (MPs; 1 μm to 5 mm in diameter) [1,2,3] are receiving increasing attention as persistent environmental pollutants; current knowledge about exposure levels and possible hazardous effects of MPs on human health are limited. Human exposure to MPs and/or nanoplastics (NPs; ≤100 nm in diameter) primarily occurs through the oral, inhalation, dermal or parenteral routes [4]. Ingestion of MP-NP particles is likely to represent the main route of exposure in humans because they can be ingested by eating contaminated seafood [4], sugar [5], salt [6,7], beer [8], tap water [6,9], and bottled water [10,11]. The gastrointestinal tract (GIT) is the most likely site of primary exposure, the intestinal absorption of MPs is predicted to be low [16,17]

Methods

Results

Conclusion