SARS-CoV-2 Spike Protein Induces Time-Dependent and Brain-Region-Specific Alterations in Ferroptosis Markers: A Preliminary Study in K18-hACE2 Mice

Post-COVID syndrome comprises persistent neuropsychiatric manifestations for more than 12 weeks after recovery from acute SARS-CoV-2 infection, yet its underlying pathophysiology is unclear. Ferroptosis, an iron-dependent form of cell death with three hallmarks, iron dysregulation, antioxidant failure, and lipid peroxidation, seems to be involved in COVID-19/post-COVID-19 pathophysiology. Here, we administered the SARS-CoV-2 spike protein S1 subunit intranasally to K18-hACE2 transgenic mice and quantified ferroptotic marker protein expression in four brain regions (hippocampus, prefrontal cortex, cerebellum, and olfactory bulb) at 2, 6, and 12 weeks post-administration, alongside ultrastructural assessment by transmission electron microscopy (TEM) that was limited to the hippocampus and prefrontal cortex. Two-way ANOVA revealed region- and time-dependent modulation of iron-handling, antioxidant, and lipid peroxidation markers. In the hippocampus, FPN1 was significantly increased at 2 weeks, while TFR1 showed a time-dependent pattern without significant week-specific differences. In the prefrontal cortex, DMT1 significantly increased at 2 weeks, and GPx4 showed an overall treatment effect with a trend of increase at 6 weeks. The cerebellum exhibited early increases in FPN1 and GPx4 and a delayed increase in MDA-conjugated proteins. In the olfactory bulb, FPN1 increased at 12 weeks, with GPx4 showing an overall treatment effect and an early trend of decrease. TEM identified ferroptosis-consistent features in the hippocampus and prefrontal cortex at all time points. These findings suggest that spike protein exposure may be associated with time-dependent and brain-region-specific alterations of ferroptosis-related markers. These preliminary findings are based on a limited sample size, which needs further research to elucidate the clinical implication and to study the mechanism in more depth as well as future validation with pharmacological inhibitors.