Immunometabolic Signature and Tauopathy Markers in Blood Cells of Progressive Supranuclear Palsy.

Background: Peripheral immune cells critically contribute to the clinical-pathological progression of neurodegenerative diseases and also represent a reliable frame for translational applications. However, data on progressive supranuclear palsy (PSP) are almost scarce in this regard.

Objective: Our goal is to provide a broad biological characterization of peripheral immune cells in a selected PSP cohort.

Methods: Seventy-one PSP patients scored on the PSP Rating Scale (PSPRS), and 59 controls were enrolled. The blood cell count was collected, together with the neutrophil-to-lymphocyte ratio (NLR) calculation. In a subgroup of patients and controls, the peripheral blood mononuclear cells (PBMCs) were analyzed by the mitochondrial bioenergetic performance and the western blot assay of the nuclear factor erythroid 2-related factor (NRF2)/heme oxygenase 1 (HO-1) pathway and the total tau (t-tau) and phosphorylated tau (p-tau) proteins. Case-control comparison and correlation analyses were performed.

Results: PSP patients had a NLR higher than controls, with increased circulating neutrophils. The leukocyte metabolism was also globally increased and the NRF2/HO-1 pathway activated in patients. P-tau, but not t-tau, significantly accumulated in PSP PBMCs and inversely correlated with the PSPRS.

Conclusions: PSP displays a systemic inflammatory shift of the peripheral immunity, which may justify a metabolic reprogramming of the blood leukocytes. Consistently, the NRF2/HO-1 pathway, a master regulator of inflammatory and metabolic response, was activated. PBMCs also engulf tau proteins, especially p-tau, in a way inverse to the disease severity, allowing for a peripheral tracking of tauopathy in patients. Immunometabolic targets may, therefore, gain relevance to PSP in biomarker or therapeutic purposes. © 2024 International Parkinson and Movement Disorder Society.