Effects of sodium metabisulfite on pyroptosis, mitophagy and degranulation in mast cells.

Sodium metabisulphite (SMB) is the most used foods and drugs antioxidant among sulfites. So far, there were few studies about its harm, especially in mast cells. Our study was to investigate the effects of SMB on mitophagy and pyroptosis in mast cells. The results revealed that SMB dose-dependently promoted the expressions of NLRP3, GSDMD-N and other marker proteins of pyroptosis. Knockdown of GSDMD, NLRP3 inhibitor, mitophagy activator and mtROS inhibitor all reversed the changes in pyroptosis indicators caused by SMB. Considering the degranulation characteristics of mast cells and the sensitization of sulfite, we examined the effects of the above inhibitors on the degranulation of mast cells caused by SMB. The results showed that SMB-mediated mast cell degranulation was significantly inhibited by the above inhibitors. Meanwhile, we used immunofluorescence co-localization experiments and found that GSDMD pore-forming protein and histamine co-localized near the cell membrane. Overall, evidence suggested that SMB caused pyroptosis by inhibiting mitophagy, leading to mast cell degranulation. These findings are of great significance to the sensitization mechanism of SMB and provide a new insight into SMB toxicology and mast cell degranulation.