Inhibition or deletion of hydroxylases-Prolyl-4-hydroxyases 3 alleviates lipopolysaccharide-induced neuroinflammation and neurobehavioral deficiency

Abstract It is well known that neuroinflammation plays a key role in neurodegenerative diseases. Hypoxia-inducible factor(HIF) and its hydroxylases-Prolyl-4-hydroxyases (PHDs) have been found to modulate the inflammatory processes.Here,the effects of PHDs enzyme onlipopolysaccharide-induced neuroinflammation and neurocognitivedeficits were investigated. BV2 microglia cells were stimulated by LPS(1μg/ml) as neuroinflammation model in vitro. Dimethyloxalylglycine(DMOG, 100μM) and PHD3-siRNA wereused to suppress the expression of PHD3.In vivo, mice received consecutive intraperitoneal injection of LPS(500μg/kg) for 7 days, and intraperitoneal injection of DMOG (100mg/kg) was applied 1 hour before LPS at the same days. Several neurobehavioral tests (Open field, Novel object recognition and Morris water maze) were used to measure cognitive function. RT-qPCR and Western blotting were used to investigate the expression of inflammatory cytokines, HIF-PHDs protein. Metabolic reprogramming was measured by seahorse method. The results revealed that LPS induced neuroinflammation and PHD3 expression in vivo and vitro. DMOG and PHD3knockout decreased expression of inflammatory cytokines and improved the metabolic reprogramming caused by LPS treatment. Furthermore, pretreatment of DMOG reversed learning and memory deficits in systemic LPS-exposed mice through anti-neuroinflammation, which is independent of DMOG angiogenesis. These findingssuggested that PHD3 may mediate LPS-induced microglial activation and neuroinflammation-associated neurobehavioral deficits.