Dynamic redox profiling in aneurysmal subarachnoid haemorrhage identifies glutathione reductase deficit in delayed cerebral ischemia

Introduction

Aneurysmal subarachnoid hemorrhage (aSAH) remains a highly lethal cerebrovascular event, with delayed cerebral ischemia (DCI) as a major determinant of poor outcome. Increasing evidence points to oxidative stress as a central mechanism of secondary brain injury, driven by hemoglobin-derived reactive oxygen species that disrupt vascular tone and endothelial function. The brain’s antioxidant defense becomes dysregulated after aSAH, potentially amplifying injury and contributing to DCI. Understanding the dynamics of these redox pathways is crucial for identifying clinically relevant biomarkers and novel therapeutic targets.

Methods

Between 2025 and March 2026, plasma samples were collected from 47 patients with aneurysmal subarachnoid hemorrhage (aSAH) and 44 age- and sex-matched healthy controls. Among the aSAH cohort, 9 patients (19.1%) developed delayed cerebral ischemia (DCI). In aSAH patients, blood samples were obtained at predefined time points (days 0, 2, 4, 6, and discharge), while controls were sampled once. The following oxidative stress-related parameters were measured: extracellular superoxide dismutase (SOD3), glucose-6-phosphate dehydrogenase (G6PD), glutathione peroxidase-3 (GPX3), thioredoxin reductase 1 (TRXR1), glutathione reductase (GR), and peroxiredoxin 4 (PRDX4).

Normality of distribution was assessed using the Shapiro–Wilk test. Due to non-normal distribution of variables, non-parametric statistical tests were applied. All analyses were performed using Statistica 13.1 PL (TIBCO Software Inc.).

Results

There were no significant age differences. GPX3 showed the most consistent and robust signal - patients with aSAH demonstrated significantly reduced GPX3 levels compared to controls from day 2 to discharge (p=0.017, p<0.001, p=0.011, and p=0.009; respectively). This pattern was characterized by an early nadir followed by gradual recovery over time, consistent across DCI and non-DCI subgroups.

In contrast, differences between DCI and non-DCI patients were selective and pathway-specific. SOD3 was significantly higher in DCI patients at day 2 (p=0.047), with a consistent upward trend at subsequent time points. GR was significantly lower in DCI patients at baseline (day 0: p=0.048) and again at discharge (p=0.027), indicating impaired regeneration of reduced glutathione. No significant differences were observed between DCI and non-DCI groups for other parameters.

Aside from GPX3, no significant differences were observed between aSAH patients and controls for the remaining biomarkers, suggesting that GPX3 captures a distinct and early systemic response to hemorrhage.

Conclusions

aSAH triggers a rapid collapse of glutathione-dependent antioxidant defenses, evidenced by early and sustained depletion of GPX3, consistent with acute exhaustion of redox buffering capacity in the immediate post-hemorrhagic phase. DCI emerges on the background of a distinct redox imbalance, characterized by increased SOD3 and decreased glutathione reductase, reflecting a critical uncoupling between reactive oxygen species generation and antioxidant regeneration. This pattern places the glutathione axis at the core of secondary brain injury after aSAH, where both accelerated consumption (GPX3) and impaired recycling (GR) contribute to oxidative vulnerability. Notably, the temporal trajectory that provides clinically meaningful insight, with GPX3 and GR dynamics offering promise for risk stratification and mechanistic monitoring of DCI. Together, these findings position redox failure, and specifically disruption of glutathione homeostasis, as a central and potentially targetable mechanism in aSAH.

Funding: This study was funded by NCN (grant no. 2024/53/B/NZ5/00343).

References

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