Lipid metabolic response to polystyrene particles in nematode Caenorhabditis elegans.

Nanoplastics can be used in various fields, such as personal care products. Nevertheless, the effect of nanoplastic exposure on metabolism and its association with stress response remain largely unclear. Using Caenorhabditis elegans as an animal model, we determined the effect of nanopolystyrene exposure on lipid metabolism and its association with the response to nanopolystyrene. Exposure (from L1-larave to adult day-3) to 100 nm nanopolystyrene (≥1 μg/L) induced severe lipid accumulation and increase in expressions of mdt-15 and sbp-1 encoding two lipid metabolic sensors. Meanwhile, we found that SBP-1 acted downstream of intestinal MDT-15 during the control of response to nanopolystyrene. Intestinal transcriptional factor SBP-1 activated two downstream targets, fatty acyl CoA desaturase FAT-6 and heat-shock protein HSP-4 (a marker of endoplasmic reticulum unfolded protein response (ER UPR)) to regulate nanopolystyrene toxicity. Both MDT-15 and SBP-1 were involved in the activation of ER-UPR in nanopolystyrene exposed nematodes. Moreover, SBP-1 regulated the innate immune response by activating FAT-6 in nanopolystyrene exposed nematodes. In the intestine, function of MDT-15 and SBP-1 in regulating nanopolystyrene toxicity was under the control of upstream signaling cascade (PMK-1-SKN-1) in p38 MAPK signaling pathway. Therefore, our data raised an important molecular basis for potential protective function of lipid metabolic response in nanopolystyrene exposed nematodes.