S100A8 aggravates sepsis-associated encephalopathy by promoting PFKFB3-dependent glycolysis and microglial...

Sepsis-associated encephalopathy (SAE) is a common and severe neurological complication of sepsis that markedly worsens long-term outcomes. Growing evidence suggest that metabolic reprogramming in microglia is a major driver of neuroinflammation in SAE; however, the molecular mechanisms that altered metabolism and inflammatory responses remain unclear.

Transcriptomic data from public hippocampal datasets of SAE mice were analyzed to identify potential molecular drivers. We established a CLP-induced SAE model and performed AAV-mediated knockdown. For in vitro validation, BV2 microglia were treated with LPS to simulate neuroinflammation. Mechanistic validation was conducted using both genetic and pharmacological interventions. Cellular metabolism was examined through extracellular flux analysis and metabolite detection. Inflammatory responses were evaluated by cytokine profiling, and disease phenotypes were assessed using behavioral tests and histological analyses.

S100A8 was markedly upregulated in activated microglia during SAE. Its knockdown reduced microglial activation, protected hippocampal neurons, and improved cognitive performance. Transcriptomic profiling identified PFKFB3 as a downstream glycolytic target of S100A8. Mechanistically, S100A8 activated the PI3K/AKT/HIF-1α signaling cascade, thereby upregulating PFKFB3 and promoting glycolytic reprogramming and cytokine release. Functionally, S100A8 knockdown lowered lactate production and LDH activity, while reducing TNF-α, IL-6, and IL-1β secretion. Rescue experiments confirmed that PFKFB3 mediates the glycolytic and pro-inflammatory effects of S100A8.

This study demonstrates that S100A8 exacerbates SAE-related neuroinflammation and cognitive impairment by driving microglial metabolic reprogramming toward glycolysis via the PI3K/AKT/HIF-1α-PFKFB3 pathway. These findings highlight a mechanistic link between S100A8 and microglial metabolic reprogramming and neuroinflammation, and suggest that S100A8 could be a promising target for therapeutic intervention in SAE.