Blood-based biomarkers of ferroptosis in Parkinson's disease

As Parkinson's disease progresses, patients require second-line treatments such as subthalamic stimulation, the benefits of which may be diminished by the onset of non-dopaminergic axial motor and cognitive disorders. This study aimed to identify blood biomarkers of ferroptosis for predicting the progression of Parkinson's disease at the stage of L-DOPA-related complications.

We analyzed 598 blood samples from patients with PD enrolled in the French multicentric PREDISTIM study. Neurofilament light chain, 4-hydroxy-2-nonenal, glutathione peroxidase activity, ferritin, alpha-synuclein and selenium levels were determined by electrochemiluminescence, ELISA or inductively coupled plasma mass spectrometry. We assessed three single-nucleotide polymorphisms in ACSL4 and GPX4 genes, two key players in ferroptosis. Overall clinical outcomes were evaluated at baseline and one-year post-surgery.

At baseline, UPDRS III-Worst OFF was positively correlated with log-4-HNE (p = 0.007). PDQ-39 was negatively correlated with log-ferritin concentration (p = 2.38*10^-4), selenium concentration (p = 0.033) and the rs7887981 in the ACSL4 gene (p = 0.033). Milder cognitive problems were correlated with the rs139736475 in ACSL4 (p = 0.028). One-year post-surgery, change in UPDRS III-Worst OFF was inversely correlated with log-4-HNE levels (p = 0.002).This association remained significant after multivariate analysis and correction for multiple testing.

Our results strongly support an association between 4-HNE levels and the progression of motor disability in advanced PD. They also provide multiple lines of evidence favoring a role for ferroptosis in PD progression. Subject to further validation, they could therefore be used to select and stratify patients for future clinical trials.

Cohort registered with ClinicalTrials.gov: NCT02360683, on January 2015.