Propofol Ameliorates Exaggerated Human Neutrophil Activation in a LPS Sepsis Model

Abstract

Background: Sepsis is a leading cause of morbidity and mortality worldwide. Many patients suffering from sepsis are treated on intensive care units and many of them require mechanical ventilation under sedation or general anesthesia. Propofol, a drug used for these purposes, is known to interact with polymorphonuclear granulocytes (PMNs). Therefore, the aim of this study was to investigate the influence of propofol on PMN functions after experimental Gram-negative induced sepsis using lipopolysaccharide (LPS) stimulation.

Methods: A total of 34 granulocyte-enriched samples were collected from healthy subjects. PMNs were isolated by density gradient centrifugation and incubated simultaneously with either 6 µg/mL or 60 µg/mL propofol, or none (control). Additionally, the experimental sepsis samples were incubated with either 40 pg/mL or 400 pg/mL LPS. Live cell imaging was conducted in order to observe granulocyte chemotactic migration, ROS production, and NETosis. Flow cytometry was used to analyze viability and antigen expression.

Results: Propofol led to significantly reduced PMN track length (p < 0.001) and track speed (p < 0.014) after LPS-induced sepsis in a dose-dependent manner. NETosis (p = 0.018) and ROS production (p = 0.039) were accelerated by propofol without LPS incubation, indicating improved immune function. Propofol also ameliorated LPS-induced increased NETosis and ROS-production. Antigen expression for CD11b, CD62l and CD66b was unaffected by propofol.

Conclusion: Propofol improves LPS-induced exaggerated PMN activation in an ex vivo model. Beneficial effects due to restored immune function in septic patients might be possible, but needs further investigation.

Keywords: LPS; immune modulation; polymorphonuclear neutrophils; propofol; sepsis.

Figure 1

Track length [µm] depending on propofol concentration [0 – 6 – 60 µg/mL] per time frame [min]. Some upper outliers (circles) and extreme values (asterisks) are cut off for better comparability of the medians and boxes.

Figure 2

(A) Track length [µm] depending on LPS concentration [0 – 40 – 400 pg/mL] per time frame [min] and without propofol. Some upper outliers (circles) and extreme values (asterisks) are cut off for better comparability of the medians and boxes. (B) Track length [µm] depending on LPS concentration [0 – 40 – 400 pg/mL] per time frame [min] with a propofol concentration of 6 µg/mL. Some upper outliers (circles) and extreme values (asterisks) are cut off for better comparability of the medians and boxes. (C) Track length [µm] depending on LPS concentration [0 – 40 – 400 pg/mL] per time frame [min] with a propofol concentration of 60 µg/mL. Some upper extreme values (asterisks) are cut off for better comparability of the medians and boxes.

Figure 3

(A) ET₅₀NET values [min] depending on propofol concentration [0 – 6 – 60 µg/mL] without LPS. (B) ET₅₀MPO [min] depending on propofol concentration [0 – 6 – 60 µg/mL] without LPS.

Figure 4

Respiratory burst activity expressed by median fluorescence intensity (MFI) after stimulation by fMLP and TNFα, depending on DMSO and propofol concentration [6 µg/mL vs 60 µg/mL].