Objective To explore the role and mechanism of the Sirt3/NLRP3 pathway in macrophages during the inflammatory response of human monocyte-derived macrophages induced by paraquat(PQ), with the aim of providing new perspectives for treating lung injury caused by PQ poisoning.

Methods Human monocyte leukemia cells (THP-1) were treated with 100 ng/mL phorbol 12-myristate 13-acetate(PMA) for 36 hours to induce differentiation into THP-1 macrophages. After cell adhesion, THP-1 macrophages were exposed to varying concentrations of PQ(0, 200, 400, 600, 800, 1 000, 1 200 μmol/L) for 24 hours. Cell viability was assessed using a CCK-8 assay to determine an appropriate dose of PQ for subsequent experiments. Ganoderic acid D (GAD), a Sirt3 agonist, was used to divide THP-1 macrophages into control, PQ, GAD, and PQ + GAD groups. After 24 hours of respective treatments, cells were collected. Reverse Transcription-PCR (RT-PCR) was performed to measure Sirt3 mRNA expression levels; Western blot was employed to detect the expression levels of NOD-like receptor thermal protein domain containing protein 3 (NLRP3), cysteinyl aspartate specific proteinase-1 (Caspase-1), and interleukin-1β (IL-1β) proteins. Immunofluorescence was used to examine NLRP3 expression, while intracellular adenosine triphosphate (ATP) and reactive oxygen species (ROS) levels were assessed using respective detection kits.

Results PQ significantly reduced Sirt3 protein expression in THP-1 macrophages (P < 0.001), leading to decreased intracellular ATP levels, increased ROS levels, and elevated protein expression levels of NLRP3, Caspase-1, and IL-1β. Following the addition of GAD, relative to the PQ group, Sirt3 mRNA levels in THP-1 macrophages were significantly upregulated, ROS levels decreased, while NLRP3, Caspase-1, and IL-1β protein levels were markedly reduced. Cell viability was also improved. All the above differences were statistically significant (P < 0.05).

Conclusions PQ treatments inhibited Sirt3 protein expression in THP-1 macrophages, increased ROS levels, and activated the NLRP3 inflammasome, thereby inducing an inflammatory response in THP-1 macrophages.