Inhibiting ferroptosis in brain microvascular endothelial cells: A potential strategy to mitigate polystyrene nanoplastics‒induced blood‒brain barrier dysfunction.

Polystyrene nanoplastics (PS-NPs), a group of ubiquitous pollutants, may injure the central nervous system through the blood‒brain barrier (BBB). However, whether exposure to PS-NPs contributes to BBB disruption and the underlying mechanisms are still unclear. In vivo, we found that PS-NPs (25 mg/kg BW) could significantly increase BBB permeability in mice and downregulate the distribution of the tight junction-associated protein zona occludens 1 (ZO-1) in brain microvascular endothelial cells (BMECs). Using an in vitro BBB model, exposure to PS-NPs significantly reduced the transendothelial electrical resistance and altered ZO-1 expression and distribution in a dose-dependent manner. RNA-seq analysis and functional investigations were used to investigate the molecular pathways involved in the response to PS-NPs. The results revealed that the ferroptosis and glutathione metabolism signaling pathways were related to the disruption of the BBB model caused by the PS-NPs. PS-NPs treatment promoted ferroptosis in bEnd.3 cells by inducing disordered glutathione metabolism in addition to Fe2+ and lipid peroxide accumulation, while suppressing ferroptosis with ferrostatin-1 (Fer-1) suppressed ferroptosis-related changes in bEnd.3 cells subjected to PS-NPs. Importantly, Fer-1 alleviated the decrease in ZO-1 expression in bEnd.3 cells and the exacerbation of BBB damage induced by PS-NPs. Collectively, our findings suggest that inhibiting ferroptosis in BMECs may serve as a potential therapeutic target against BBB disruption induced by PS-NPs exposure.

Involvement of the JNK/HO­1/FTH1 signaling pathway in nanoplastic­induced inflammation and ferroptosis of BV2 microglia cells.

Nanoplastics (NPs) are a newly discovered type of environmental pollutant. The potential for neurotoxicity caused by NPs and their mechanisms are unclear. The present study aimed to determine the molecular mechanism underlying neurotoxicity induced by NPs. Microglia (BV2) cells were used for in vitro studies, and it was found that NPs invaded cells, activated inflammasomes, induced the release of significant quantities of inflammatory factors by detection of inflammatory response­associated proteins through Western blot and ELISA. By detection of FITC, SOD, GSH, cellular iron level, and ferroptosis­related proteins, it was found that NPs compromised the anti­oxidative mechanisms of cells, increased intracellular lipid peroxidation and Fe2+ concentration and triggered inflammatory reactions and ferroptosis. Pretreatment with reactive oxygen species (ROS) inhibitor N­acetylcysteine (NAC) alleviated induction of inflammatory reactions and ferroptosis of cells. In addition, inhibiting expression of c­Jun N­terminal kinase (JNK) increased expression of heme oxygenase (HO­1), resulting in decreased ferroptosis, indicating that the JNK/HO­1 signaling pathway was involved in NP­induced effects on ferroptosis in BV2 cells. In conclusion, NPs could induce inflammatory responses and ferroptosis in BV2 cells. JNK/HO­1 mediated ferroptosis may serve an important role in the toxicity of microglia induced by NPs. This study provided novel evidence for the toxic effects of NPs and highlighted a theoretical mechanistic basis for safe prevention and treatment of plastic pollution­induced neurotoxicity.

Activation of pyroptosis and ferroptosis is involved in the hepatotoxicity induced by polystyrene microplastics in mice.

Microplastics (MPs) are new environmental pollutants and have received widespread attention in recent years, but the toxicity of the MPs remains to be fully elucidated. To explore the effect of MPs on hepatotoxicity in mice and unravel the mechanism of pyroptosis and ferroptosis in the process of liver injury, we treated mice with 5.0 µm polypropylene microplastics (MPs) at 0.1, 0.5 and 1 mg/mL for 4 weeks. Results revealed that MPs could damage liver structure and function with broken and reduced mitochondrial cristae, as well as increased levels of aspartate minotransferase (AST), alanine aminotransferase (ALT), AST/ALT, alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). Treatment with MPs resulted in pyroptosis as evidenced by increasing expressions of interleukin IL-1ß, IL-18. Additionally, MPs were shown to induce the NOD-like receptor protein 3 (NLRP3) inflammasomes and apoptosis associated speck-like protein (ASC) containing a caspase recruitment domain activation in liver tissue, enabling activation of Caspase-1-dependent signaling pathway induced by inflammatory stimuli resulting from oxidative stress. In addition, the increase of malondialdehyde (MDA) and decrease of glutathione (GSH) and superoxide dismutase (SOD) in the liver indicated that MPs could induce oxidative damage. Moreover, MPs induced lipid peroxidation in the liver of mice could activate the expression of ferroptosis related proteins, including iron metabolism, such as transferrin receptor (TFRC) was active but ferritin heavy chain 1 (FTH1) was inhibited; amino acid metabolism, such as XCT system and glutathione peroxidase 4 (GPX4) were inhibited; lipid metabolism, such as acyl-CoA synthetase long-chain family member 4 (ACSL4) was inhibited. Collectively, these findings evidenced that pyroptosis and ferroptosis occurred in MPs-induced liver injury accompanied by intense oxidative stress and inflammation.