Extensive environmental pollution by microplastics has increased the risk of human exposure to plastics. However, the biosafety of polypropylene microplastics (PP-MPs), especially of PP particles < 10 μm, in mammals has not been studied. Thus, here, we explored the mechanism of action and effect of exposure to small and large PP-MPs, via oral ingestion, on the mouse intestinal tract. Male C57BL/6 mice were administered PP suspensions (8 and 70 μm; 0.1, 1.0, and 10 mg/mL) for 28 days. PP-MP treatment resulted in inflammatory pathological damage, ultrastructural changes in intestinal epithelial cells, imbalance of the redox system, and inflammatory reactions in the colon. Additionally, we observed damage to the tight junctions of the colon and decreased intestinal mucus secretion and ion transporter expression. Further, the apoptotic rate of colonic cells significantly increased after PP-MP treatment. The expression of pro-inflammatory and pro-apoptosis proteins significantly increased in colon tissue, while the expression of anti-inflammatory and anti-apoptosis proteins significantly decreased. In summary, this study demonstrates that PP-MPs induce colonic apoptosis and intestinal barrier damage through oxidative stress and activation of the TLR4/NF-κB inflammatory signal pathway in mice, which provides new insights into the toxicity of MPs in mammals.

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Polystyrene (PS) and di-(2-ethylhexyl) phthalate (DEHP) exist widely in the environment. However, their distribution in organisms remains unclear. We used three sizes (50 nm, 500 nm, and 5 μm) of PS and DEHP to study the distribution and accumulation of PS, DEHP, and mono(2-ethylhexyl) phthalate (MEHP) in mice and nerve cell models (HT22 and BV2 cells) and their potential toxicity. Results showed that PS entered the blood of mice, and the distribution of different particle sizes in different tissues was different. After the combined exposure to PS and DEHP, PS carried DEHP, which significantly increased the DEHP content and MEHP content and the highest content of MEHP was in the brain. With the decrease in PS particle size, the contents of PS, DEHP, and MEHP in the body increased. The levels of inflammatory factors were increased in the serum of the PS or/and DEHP group. In addition, 50 nm polystyrene can carry MEHP into nerve cells. These results suggest for the first time that PS and DEHP combined exposure can induce systemic inflammation, and the brain is an important target organ of PS and DEHP combined exposure. This study may serve as a reference for further evaluation of the neurotoxicity induced by combined exposure to PS and DEHP.

The outbreak of Sargassum horneri in a large area in China has not only posed a serious threat to the ecological environment and human life in the coastal waters, but also hindered the development of waterway transportation and the local economy. Therefore, we isolated polysaccharides from S. horneri, named SHP, and evaluated the antioxidant activity of SHP in vitro and in vivo by exploring the effect of SHP on H2O2-induced African green monkey kidney cell (Vero cell) and zebrafish. The results showed that SHP could scavenge DPPH radicals, hydroxyl radicals (·OH), superoxide anion radicals (O_2), and total antioxidant capacity (T-AOC), which respectively were 68%, 65.48 U mL− 1, 84.86 U mL− 1 and 33.55; In addition, SHP can increase SOD, CAT and GSH-PX activities in zebrafish; It also effectively inhibits MDA and ROS levels in Vero cells and zebrafish to weaken oxidative damage caused by H2O2, to realize the protective effect of SHP on Vero cells and zebrafish. In conclusion, SHP has the potential as a natural antioxidant. SHP can be considered for use as a natural antioxidant in the biomedical, cosmetic, and food industries, thus alleviating environmental stress caused by S. horneri, and realizing resource utilization.