Hexokinase 2 Exacerbates Mitochondrial Damage, Neuroinflammation, and Lipid accumulation by promoting ACSL4 ISGylation in Sepsis-Associated Encephalopathy

Metabolic reprogramming is often observed in sepsis-associated encephalopathy (SAE). However, little is known about the aberrant metabolic genes involved in mitochondrial damage, neuroinflammation, and lipid accumulation in microglial cells. Here, we show that hexokinase 2 (HK2) is upregulated and is strongly associated with the inflammatory response and lipid metabolism in lipopolysaccharide-induced BV2 cells. Genetic silencing or pharmacological inhibition of HK2 attenuates mitochondrial damage in vitro. Downregulation of HK2 lowered the NOD-like receptor signaling family pyrin domain containing three activations, both in BV2 cells and in the hippocampus of cecal ligation and puncture-induced male septic mice. Moreover, the inhibition of HK2 promoted lipid droplet reduction and activated mammalian target of rapamycin-mediated autophagy. Mechanistically, HK2 knockdown in microglial cells reduced the ISGylation of Acyl-CoA Synthetase Long-chain Family Member 4 (ACSL4) during lipid metabolism by interferon-stimulated gene 15 (ISG15). Notably, ISG15 effectively down-regulated the expression of ACSL4 in vitro. Our findings provide new mechanistic insights of HK2 in microglial cells through regulation of ACSL4 ISGylation, suggesting a promising therapeutic strategy for treating SAE by targeting HK2.