Monocyte Metabolism and Function in Patients Undergoing Cardiac Surgery

Area of Science:

• Immunometabolism
• Cardiac Surgery
• Systemic Inflammation

Background:

• Cardiopulmonary bypass (CPB) is associated with systemic inflammation and increased patient morbidity.
• Understanding the metabolic changes in immune cells like monocytes during CPB is crucial for mitigating adverse effects.

Purpose of the Study:

• To investigate the metabolic profile of monocytes in patients undergoing CPB compared to healthy controls.
• To assess changes in monocyte metabolism and immune marker expression at various time points before and after CPB.

Main Methods:

• Prospective observational study including 30 CPB patients and 20 controls.
• Monocyte isolation and metabolic analysis using Seahorse technology at baseline, 4h, and 24h post-CPB.
• Flow cytometry for PD-L1, PD-L2, VISTA, and HLA-DR; plasma cytokine analysis.

Main Results:

• CPB significantly elevated plasma IL-6 levels, indicating an inflammatory response.
• Monocytes exhibited a shift towards aerobic glycolysis post-CPB, with reduced response to ex vivo lipopolysaccharide stimulation.
• Altered monocyte metabolism favoring aerobic glycolysis was observed even before CPB initiation compared to controls.

Conclusions:

• Monocyte immunometabolism shifts from oxidative phosphorylation to aerobic glycolysis after CPB, linked to inflammation.
• This study is the first to demonstrate altered monocyte immunometabolism in cardiac surgery patients, even pre-operatively.
• Findings suggest potential therapeutic targets to prevent CPB-induced inflammatory effects.