MLKL Aggravates Ox-LDL-Induced Cell Pyroptosis via Activation of NLRP3 Inflammasome in Human Umbilical Vein Endothelial Cells

Atherosclerosis is a progressive chronic inflammation in the arterial walls. It is believed that the deposition of low-density lipoprotein (LDL) and its damage to endothelial cells play a vital role in atherosclerosis. Oxidized LDL (Ox-LDL) was confirmed to induce endothelial cell pyroptosis which plays an important role in intima inflammation and the development of atherosclerosis, but the underlying molecular mechanism needs to be explored. Here, we showed that ox-LDL upregulated the expression of mixed lineage kinase domain-like (MLKL) protein at both the mRNA and protein levels in endothelial cells, associated with the augment of pro-caspase-1 cleavage, interleukin-1β (IL-1β) maturation, pro-IL-1β production, and lactate dehydrogenase (LDH) release. Overexpression of MLKL substantially aggravated ox-LDL-induced increasing levels of caspase-1, IL-1β, pro-IL-1β, and LDH. MLKL-induced caspase-1 activation and IL-1β maturation were abolished by NLR family, pyrin domain-containing 3 (NLRP3) specific inhibitor MCC950, or extracellular high potassium concentration. Our findings indicated that MLKL is essential for regulation of ox-LDL-induced pyroptosis and inflammation through the activation of NLRP3 inflammasome, and suggested that MLKL could act as potential therapeutic targets to ameliorate atherosclerosis-related diseases.