Authors: Lin M-C et al.
Anesthesiology, February 12, 2026, 10.1097/ALN.0000000000005978
This study explored how overdose exposure to propofol emulsion may injure human peripheral neutrophils and provides mechanistic insight relevant to propofol infusion syndrome (PRIS). PRIS is a rare but severe complication associated with excessive or prolonged propofol exposure and is typically characterized by metabolic derangements, lipid abnormalities, organ dysfunction, and cellular injury. The authors focused specifically on neutrophils, which are important immune effector cells and may be especially vulnerable to lipid-mediated and oxidative injury.
Using an ex vivo human whole-blood model, the investigators exposed peripheral blood cells to overdose propofol emulsion and then used flow cytometry and molecular assays to evaluate lipid accumulation, cell death pathways, and mitochondrial function. Their findings suggest that excessive propofol emulsion can trigger a complex, mixed cell death program known as PANoptosis.
PANoptosis refers to the coordinated activation of multiple programmed cell death pathways, particularly apoptosis, pyroptosis, and necroptosis, rather than a single isolated mechanism. In this study, neutrophils exposed to overdose propofol emulsion demonstrated evidence of all three pathways. Apoptosis was supported by cleaved caspase-3 detection. Necroptotic signaling was associated with increased phosphorylated RIPK1. Pyroptotic activity was linked to cleaved caspase-1 expression. Together, these findings supported the conclusion that neutrophils were undergoing combined PANoptotic death rather than one dominant pathway alone.
A central observation was the marked accumulation of lipid droplets within neutrophils after overdose propofol emulsion exposure. These intracellular lipid droplets correlated strongly with changes in cell granularity and with the extent of cell death. This suggests that lipid handling abnormalities are not just an epiphenomenon, but may be mechanistically linked to cytotoxicity.
The study further implicated free fatty acids as an important upstream driver. When lipolysis was inhibited, both lipid droplet accumulation and PANoptotic cell death were reduced. This supports the hypothesis that breakdown products from the lipid emulsion, especially free fatty acids, contribute significantly to neutrophil injury.
Oxidative stress also appeared to play a major role. The investigators found increased reactive oxygen species, particularly mitochondria-related reactive oxygen species, after exposure to overdose propofol emulsion. These reactive oxygen species correlated with lipid droplet burden, suggesting an interaction between lipid overload and oxidative injury. Mitochondrial dysfunction was demonstrated by loss of mitochondrial membrane potential, further supporting the idea that propofol emulsion toxicity disrupts cellular energetics and mitochondrial integrity.
Importantly, the use of reactive oxygen species inhibitors mitigated mitochondrial dysfunction and reduced PANoptosis. This finding suggests that oxidative stress is not merely associated with cell injury, but is functionally involved in the pathway leading to neutrophil death.
Overall, the study proposes a pathophysiologic model in which overdose propofol emulsion leads to increased lipolysis, free fatty acid generation, intracellular lipid droplet accumulation, oxidative stress, mitochondrial injury, and ultimately PANoptotic neutrophil death. This may help explain some of the immune dysfunction and cytotoxic damage seen in propofol infusion syndrome.
The article is mechanistic and preclinical, so its direct bedside implications remain limited for now. However, it offers a useful biologic framework for understanding PRIS and raises the possibility that targeting lipid metabolism or oxidative stress could become part of future prevention or treatment strategies.
What You Should Know
This study is important because PRIS remains poorly understood mechanistically, especially at the level of immune cell injury.
The main message is that overdose propofol emulsion does not appear to kill neutrophils through just one pathway. Instead, it activates a combined death program involving apoptosis, pyroptosis, and necroptosis.
Lipid droplet accumulation and free fatty acid generation appear central to the injury process, which fits with the lipid-rich nature of propofol emulsion and the dyslipidemia often seen in PRIS.
Mitochondrial reactive oxygen species and mitochondrial dysfunction were also strongly implicated, suggesting that oxidative stress may be a key therapeutic target.
Because this was an ex vivo model, the findings are hypothesis-generating rather than directly practice-changing, but they add meaningful mechanistic insight to the PRIS literature.
Key Points
Overdose propofol emulsion caused significant lipid droplet accumulation in human peripheral neutrophils.
Neutrophil death involved combined activation of apoptosis, necroptosis, and pyroptosis, consistent with PANoptosis.
Free fatty acids generated through lipolysis appeared to contribute to lipid accumulation and cell death.
Reactive oxygen species, especially mitochondrial reactive oxygen species, were significantly increased.
Mitochondrial dysfunction was demonstrated by loss of mitochondrial membrane potential.
Inhibiting lipolysis or oxidative stress reduced PANoptosis, suggesting possible future therapeutic targets.
Thank you to Anesthesiology for allowing us to summarize this article.