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Parkinso’s disease (PD) is a common neurodegenerative movement disorder and leucine-rich repeat kinase 2 (LRRK2) is a promising therapeutic target for disease intervention. However, the ability to stratify patients who will benefit from such treatment modalities based on shared etiology is critical for the success of disease-modifying therapies. Ciliary and centrosomal alterations are commonly associated with pathogenic LRRK2 kinase activity and can be detected in many cell types. We previously found centrosomal deficits in immortalized lymphocytes fromG2019S-LRRK2PD patients. Here, to investigate whether such deficits may serve as a potential blood biomarker for PD which is susceptible to LRKK2 inhibitor treatment, we characterized patient-derived cells from distinct PD cohorts. We report centrosomal alterations in peripheral cells from a subset of early-stage idiopathic PD patients which is mitigated by LRRK2 kinase inhibition, supporting a role for aberrant LRRK2 activity in idiopathic PD. Centrosomal defects are detected inR1441G-LRRK2andG2019S-LRRK2PD patients and in non-manifestingLRRK2mutation carriers, indicating that they acumulate prior to a clinical PD diagnosis. They are present in immortalized cells as well as in primary lymphocytes from peripheral blood. These findings indicate that analysis of centrosomal defects as a blood-based patient stratification biomarker may help nominate PD patients who will benefit from LRRK2-related therapeutics.One-sentence summaryPeripheral blood-derived cells can be employed to stratify Parkinso’s disease patients most likely to respond to LRRK2-related therapeutics.

ObjectiveThe lack of knowledge about the onset and progression of Parkinson’s disease (PD) hampers its early diagnosis and treatment. Our aim was to determine the biochemical remodeling induced by PD in a really early and pre-symptomatic stage and unveiling early potential diagnostic biomarkers adopting a multiplatform (LC-MS, GC-MS, CE-MS) untargeted metabolomics approach.Methods41,437 healthy volunteers from the European Prospective Study on Nutrition and Cancer (EPIC)-Spain cohort were followed for around 15 years to ascertain incident PD. For this study, baseline pre-clinical plasma samples of 39 randomly selected individuals (46% females, 41– 69 years old) that developed PD (Pre-PD group) and the corresponding control group (n=39, 46% females, 41–69 years old) were analyzed. The metabolic differences were investigated by univariate and multivariate data analyses, followed by pathway-based metabolite analyses to obtain possible clues on biological functions.ResultsOur results exposed significantly lower levels of seven free fatty acids in the pre-PD subjects, together with alterations in other metabolite classes. Our finding revealed alterations in fatty acids metabolism, mitochondrial dysfunction, oxidative stress, and gut-brain axis dysregulation.ConclusionsAlthough the biological purpose of these events is still unknown, the mechanisms involved in the remodelling of the suggested metabolic pathways seem to appear long before the development of PD hallmarks. These findings might be considered as worthy potential markers whose alteration might lead to the development of PD hallmarks in the future. Consequently, this study is of inestimable value since this is the first study conducted with samples collected many years before the disease development.

Gain-of kinase function variants in LRRK2 (leucine-rich repeat kinase 2) cause Parkinson’s disease (PD), albeit with incomplete and age-dependent penetrance, offering the prospect of disease-modifying treatment strategies via LRRK2 kinase inhibition. LRRK2 phosphorylates a subgroup of RabGTPases including Rab10 and pathogenic mutations enhance LRRK2-mediated phosphorylation of Rab10 at Thr73.In this study we analyse LRRK2 dependent Rab10Thr73 phosphorylation in human peripheral blood neutrophils isolated from 101 individuals using quantitative immunoblotting and mass spectrometry. Our cohort includes 42 LRRK2 mutation carriers (21 with the G2019S mutation that resides in the kinase domain and 21 with the R1441G mutation that lies within the ROC-COR domain), 27 patients with idiopathic PD, and 32 controls.We show that LRRK2 dependent Rab10 Thr73 phosphorylation is significantly elevated in all R1441G LRRKR2 mutation carriers irrespective of disease status. PD manifesting and non-manifesting G2019S mutation carriers as well as idiopathic PD samples did not display elevated Rab10 Thr73 phosphorylation. Furthermore, we analysed brain samples of 10 G2019S and 1 R1441H mutation carriers as well as 10 individuals with idiopathic PD and 10 controls. We find high variability for pRab10Thr73 phosphorylation amongst donors irrespective of genetic and disease state.We conclude that in vivo LRRK2 dependent pRab10Thr73 analysis in human peripheral blood neutrophils is a specific and robust biomarker for LRRK2 kinase activation for individuals with mutations such as R1441G that enhance pRab10Thr73 phosphorylation over 2-fold. We provide the first evidence that the LRRK2 R1441G mutation enhances LRRK2 kinase activity in a primary human cell.