PS-MPs Induced Inflammation and Phosphorylation of Inflammatory Signalling Pathways in Liver

As new pollutants, microplastics (MPs) have attracted much attention worldwide because they cause serious environmental pollution and pose potential health risks to humans. However, the toxic effects of MPs are still unclear. In this study, we analysed the inflammatory effects of 0.1 μm polystyrene microplastics (PS-MPs) on mouse and human liver cell lines. After 28 days of exposure to PS-MPs, the mice presented decreased liver index values and increased AST/ALT values. HL7702 and HepG2 were treated with PS-MPs for 24 h, and the cytotoxicity, the expression levels of inflammatory factors, and the phosphorylation of proteins in inflammation related pathways were confirmed. Compared with the control, the cell viability of these two cells significantly decreased after exposure to the PS-MPs at 1000 μm/cm², and the BMD model also exhibited a similar dose. LDH leakage and AST also increased in a dose-dependent increase after PS-MPs exposure. The relative levels of chemokines such as GM-CSF, IL-6, IL-8, and IL-12p70 were significantly greater than those in the control. Furthermore, the PS-MPs can increase the expression levels of <i>TLR4</i>, <i>MyD88,</i> and <i>NF-κB</i> and activate the phosphorylation of NF-κB and STATs. Based on these results, exposure to PS-MPs can stimulate liver inflammation and activate the TLR4/MyD88/NF-κB and JAK-STAT pathways.