Neutrophil extracellular trap formation during surgical procedures: a pilot study

Area of Science:

• Immunology
• Surgical Pathology
• Cellular Biology

Background:

• Neutrophil extracellular traps (NETs) are crucial for pathogen defense and inflammation.
• NETosis, the process of NET formation, is vital in immune responses.
• Surgical trauma can significantly influence immune cell function and patient outcomes.

Purpose of the Study:

• To investigate the impact of mild (TAVI/PAVI) and severe (ACB) surgical trauma on neutrophil extracellular trap formation (NETosis).
• To assess changes in monocytic HLA-DR expression as a marker of immune status post-surgery.
• To correlate surgical trauma severity with alterations in neutrophil and monocyte function.

Main Methods:

• Pilot study involving patients undergoing TAVI/PAVI or ACB procedures.
• Blood samples collected pre-surgery, end of surgery, and 24/48 hours post-surgery.
• Isolated neutrophils were stimulated with PMA to assess NETosis via microscopy; monocytic HLA-DR expression analyzed by flow cytometry.

Main Results:

• Both TAVI/PAVI and ACB procedures downregulated monocytic HLA-DR expression, with a more pronounced effect in ACB patients.
• NETosis rates showed no significant change over time in the TAVI/PAVI group after PMA stimulation.
• Severe surgical trauma (ACB) led to a significant decrease in PMA-induced NETosis, suggesting compromised neutrophil inducibility.

Conclusions:

• Severe surgical trauma (ACB) compromises the ability of neutrophils to form NETs upon stimulation.
• Both mild and severe surgical trauma induce a post-operative immunosuppressed state, indicated by reduced monocytic HLA-DR expression, with ACB having a greater impact.
• Potential contributing factors to immunosuppression include extracorporeal circulation and tissue damage during severe surgical procedures.