BACKGROUND:Fibronectin type Ⅲ domain-containing protein 5(FNDC5)is a muscle factor that can regulate glucose and lipid metabolism,and exert anti-inflammatory,anti-oxidative effects and improvement in insulin resistance.Moreover,FNDC5 could control various cell pyroptosis. OBJECTIVE:To explore the effect and potential mechanism of FNDC5 on macrophage pyroptosis. METHODS:(1)After completing the construction of the lentivirus virus overexpressing FNDC5 or silencing FNDC5,the THP-1 cells were transfected with the lentivirus vector.The result of transfection was detected by the expression of green fluorescence,qPCR,and western blot assay.(2)Phorbol ester induced THP-1 cells to differentiate into macrophages.Oxidized low-density lipoprotein(ox-LDL)was added to induce the cell pyroptosis model.There were six groups,i.e.,NC group,ox-LDL group,ox-LDL+MOCK1 group,ox-LDL+Ov-FNDC5 group,ox-LDL+MOCK2 group,and ox-LDL+shFNDC5 group.(3)The level of cell pyroptosis was evaluated by Hoechst 33342/propidium iodide fluorescence double staining and lactate dehydrogenase release assay.The expression levels of related molecules in THP-1 cells were analyzed by qPCR and western blot assay.The interleukin-18 and interleukin-1β in cell supernatant were detected by ELISA. RESULTS AND CONCLUSION:Compared with the ox-LDL+MOCK1 group,overexpression of FNDC5 significantly reduced the pyroptosis rate of macrophages and the release levels of lactate dehydrogenase,interleukin-1β and interleukin-18,significantly inhibited the mRNA expression of NF-κB p65,NF-κB p50,NLRP3,ASC,Caspase-1,and GSDMD,and significantly inhibited the protein expression of NF-κB p65,NF-κB p50,NLRP3,ASC,cleaved Caspase-1 and GSDMD-N.Compared with the ox-LDL+MOCK2 group,the silence of FNDC5 showed the opposite result.These findings suggest that FNDC5 attenuates pyroptosis in macrophages by inhibiting the NF-κB/NLRP3 pathway.