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‐1α/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‐1α, Nrf2, and pyroptosis related proteins NLRP3, caspase‐1, IL‐1β, 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‐1α/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‐1α and Nrf2 was significantly down‐regulated when SIRT1 was inhibited, while over‐expressed SIRT1 led to increased PGC‐1α and Nrf2 levels. Besides, miR‐181 promoted the CPF induced activation of pyroptosis and oxidative stress, as well as down‐regulated SIRT1/PGC‐1α/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‐1α/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. [ABSTRACT FROM AUTHOR]