Pyruvate Dehydrogenase Complex Activates NLRP3 Inflammasomes And Promotes Adhesion Of Monocytes To Endothelial Cells

Objective:Pyruvate dehydrogenase complex(PDC)is a mitochondria enzyme system that catalyzes pyruvate decarboxylation into acetyl coenzyme A.PDC has been implicated in a series of pathophysiological procedures including lactic acidosis,hypertension,tumor cell mutation.The role of PDC on the pathogenesis of atherosclerosis is not known.Atherosclerosis is believed to be a chronic inflammatory processing in which NLRP3 inflammasomes play critical roles.In this study,we investigated the potential roles of PDC on activation of NLRP3 inflammasomes and subsequent pathological procedures of atherosclerosis.Methods:Experiments were divided into four groups:Control,Oxidized low-density lipoprotein(OX-LDL),dichloroacetate(DCA),and ranolazine.The THP-1 cell line was used as a human monocyte/macrophage cell model.DCA(ImM)and ranolazine(5μM)were used to directly and indirectly activate PDC separately.Western blot analysis was used to determine the protein expression of NLRP3 and its downstream protein caspase-1,interleukin(IL)-1β,and IL-18.The Enzyme Linked Immune Sorbent Assay(ELISA)was used to determine the amount of IL-1β and IL-18 released into the culture supernatant.The adhesion of monocytes to endothelial cells were determined by co-culture of human umbilical vein endothelial cells(HUVEC)and THP-1 monocytes.Results:DCA,similar to OX-LDL,increased the protein expression of NLRP3 and its downstream proteins caspase-1,IL-1β,and IL-18.The amount of IL-1β and IL-18 released into supernatant was also increased with the DCA treatment,indicating activation of PDC induced the activation of NLRP3 inflammasomes in THP-1 cells.The DCA-mediated PDC and NLRP3 activation resulted in the increase in adhesion of monocytes to endothelial cells,indicating its potential roles in the initiation of atherosclerosis pathological processing.However,ranolazine,an indirect PDC activator,had no obvious effect on either the activation of NLRP3 inflammasomes determined by either Western blot or ELISA analysis,or the adhesion of monocytes to endothelial cells.Conclusion:Direct activation of PDC by DCA stimulates NLRP3 inflammasome activation in THP-1 monocytes,and subsequent monocyte adhesion to the endothelial cells.