Activated peripheral blood mononuclear cell mediators trigger astrocyte reactivity.

Area of Science:

• Neuroscience
• Immunology
• Metabolic pathways

Background:

• Sepsis causes widespread inflammation and cognitive impairment.
• Astrocytes' role in acute sepsis and their communication with peripheral immune cells is underexplored.
• Peripheral blood mononuclear cell (PBMC) mediators may influence brain function during sepsis.

Purpose of the Study:

• To investigate the communication between PBMC mediators and astrocytes during acute sepsis.
• To identify the impact of sepsis on astrocyte function and brain energy metabolism.
• To explore the role of phosphoinositide 3-kinase (PI3K) in sepsis-induced astrocyte dysfunction.

Main Methods:

• Transcriptome analysis of blood from septic patients.
• Cecal ligation and perforation (CLP) rat model for acute sepsis.
• In vivo and ex vivo brain analyses, including glucose metabolism and astrocyte reactivity.
• In vitro astrocyte cultures exposed to PBMC mediators.
• Pharmacological inhibition of PI3K.

Main Results:

• Septic patients' blood showed impaired energy-related signaling pathways.
• CLP rats exhibited brain glucose hypometabolism, astrocyte reactivity, and reduced glutamate uptake.
• PBMC mediators from septic animals induced astrocyte energetic failure in vitro.
• PI3K inhibition affected glutamate uptake but not glucose metabolism.

Conclusions:

• PBMC mediators directly influence astrocyte reactivity and contribute to brain energy failure in acute sepsis.
• Astrocyte dysfunction, including impaired glutamate uptake, is a key feature of sepsis-induced brain injury.
• PI3K pathway is implicated in sepsis-induced astrocyte dysfunction, suggesting a potential therapeutic target.