Abstract
Pyroptosis, a type of inflammatory cell death, is dependent on the inflammatory caspase-mediated cleavage of gasdermin D (GSDMD), and the subsequent pore formation on plasma membranes through which interleukin (IL)-1β and IL-18 are released from cells. During proinflammatory activation, macrophages shift their metabolism from aerobic oxidative phosphorylation to anaerobic glycolysis. Hypoxia-inducible factor (HIF)1α is involved in the induction of IL-1β gene expression as well as the metabolic shift towards glycolysis. However, the relationships between pyroptosis and glycolysis, as well as between pyroptosis and HIF1α are poorly investigated. Here we show that lipopolysaccharide (LPS) stimulation of RAW264.7 murine macrophage cells results in pyroptosis when cells are cultured in high glucose medium. During pyroptosis, HIF1α activation occurs transiently followed by downregulation to sub-basal levels. HIF1α downregulation and pyroptosis are observed when cells are stimulated with LPS under high glucose conditions. We also found that intracellular levels of methylglyoxal (MGO), a side product of glycolysis, increase when cells are stimulated with LPS under high glucose conditions. The addition of glycolysis inhibitor and rapamycin suppresses HIF1α downregulation and pyroptosis. These results show that glycolysis plays a crucial role not only in pro-inflammatory activation, but also in pyroptosis in LPS-stimulated RAW264.7 macrophages.