Chlorpyrifos activates cell pyroptosis and increases susceptibility on oxidative stress-induced toxicity by miR-181/SIRT1/PGC-1α/Nrf2 signaling pathway in human neuroblastoma SH-SY5Y cells: Implication for association between chlorpyrifos and Parkinson's disease

Background The insecticide exposure has been linked to Parkinson's disease (PD). In the present study, we used a most widely used cell line in study of PD, the SH-SY5Y cells, to investigate mechanisms of chlorpyrifos (CPF) induced cell toxicity and the possible roles of cell pyroptosis and oxidative stress in SH-SY5Y cells, as well as role of miR-181/SIRT1/PGC-1 alpha/Nrf2 signaling pathway in this process. Methods SH-SY5Y cells were treated with different concentrations of CPF. Cell viability was measured using CCK-8 assay. Cell pyroptosis was determined by immunofluorescence of caspase-1 and TUNEL assay. The miR-181 (has-miR-181-5p) level was determined by qRT-PCR. Expression of SIRT1, PGC-1 alpha, Nrf2, and pyroptosis related proteins NLRP3, caspase-1, IL-1 beta, and IL-18 was determined by both qRT-PCR and Western blotting. Results Cell viability was found to be decreased with the increased CPF concentrations. The pyroptosis related proteins, ROS levels, as well as level of caspase-1 and the TUNEL positive cells were all significantly up-regulated by CPF. Meanwhile, expression of miR-181 and pyroptosis proteins was also enhanced, while the SIRT1/PGC-1 alpha/Nrf2 signaling was inhibited by CPF. Knockdown of Nrf2 significantly up-regulated the expression of pyroptosis related proteins, ROS level, caspase-1, and the TUNEL positive cells, while over-expression of Nrf2 resulted in opposite results. The expression of PGC-1 alpha and Nrf2 was significantly down-regulated when SIRT1 was inhibited, while over-expressed SIRT1 led to increased PGC-1 alpha and Nrf2 levels. Besides, miR-181 promoted the CPF induced activation of pyroptosis and oxidative stress, as well as down-regulated SIRT1/PGC-1 alpha/Nrf2 signaling, while inhibition of miR-181 led to opposite results. Conclusions Chlorpyrifos could inhibit cell proliferation, activate cell pyroptosis and increase susceptibility on oxidative stress-induced toxicity by elevating miR-181 through down-regulation of the SIRT1/PGC-1 alpha/Nrf2 pathway in human neuroblastoma SH-SY5Y cells. This study might give deeper insights for mechanisms of CPF induced toxicity and might give some novel research targets for PD treatment.