LRRK2‐mediated Rab10 phosphorylation in immune cells from Parkinson's disease patients

Abstract

Background Leucine‐rich repeat kinase 2 is a potential therapeutic target for the treatment of Parkinson's disease, and clinical trials of leucine‐rich repeat kinase 2 inhibitors are in development. The objective of this study was to evaluate phosphorylation of a new leucine‐rich repeat kinase 2 substrate, Rab10, for potential use as a target engagement biomarker and/or patient enrichment biomarker for leucine‐rich repeat kinase 2 inhibitor clinical trials. Methods Peripheral blood mononuclear cells and neutrophils were isolated from Parkinson's disease patients and matched controls, and treated ex vivo with a leucine‐rich repeat kinase 2 inhibitor. Immunoblotting was used to measure levels of leucine‐rich repeat kinase 2 and Rab10 and their phosphorylation. Plasma inflammatory cytokines were measured by multiplex enzyme‐linked immunosorbent assay. Results Mononuclear cells and neutrophils of both controls and Parkinson's disease patients responded the same to leucine‐rich repeat kinase 2 inhibitor treatment. Leucine‐rich repeat kinase 2 levels in mononuclear cells were the same in controls and Parkinson's disease patients, whereas leucine‐rich repeat kinase 2 was significantly increased in Parkinson's disease neutrophils. Rab10 T73 phosphorylation levels were similar in controls and Parkinson's disease patients and did not correlate with leucine‐rich repeat kinase 2 levels. Immune‐cell levels of leucine‐rich repeat kinase 2 and Rab10 T73 phosphorylation were associated with plasma inflammatory cytokine levels. Conclusions Rab10 T73 phosphorylation appears to be a valid target engagement biomarker for potential use in leucine‐rich repeat kinase 2 inhibitor clinical trials. However, a lack of association between leucine‐rich repeat kinase 2 and Rab10 phosphorylation complicates the potential use of Rab10 phosphorylation as a patient enrichment biomarker. Although replication is required, increased leucine‐rich repeat kinase 2 levels in neutrophils from Parkinson's disease patients may have the potential for patient stratification. leucine‐rich repeat kinase 2 activity in peripheral immune cells may contribute to an inflammatory phenotype. © 2018 International Parkinson and Movement Disorder Society

An assessment of LRRK2 serine 935 phosphorylation in human peripheral blood mononuclear cells in idiopathic Parkinson’s disease and G2019S LRRK2 cohorts

“…Consistent with our data, they reported no differences in pS935 or total LRRK2 levels in iPD subjects compared to healthy controls. On the other hand, Atashrazm et al [15] reported higher levels of total LRRK2 levels in neutrophils from iPD cases compared to healthy controls. The apparent discrepancy between our study and [15] may be due to previously reported cell-specific regulation of LRRK2 expression [16,17].…”

“…There is only one previous report [15] on levels of pS935 and total LRRK2 in PBMCs, but these assessments were restricted to iPD and healthy controls. Consistent with our data, they reported no differences in pS935 or total LRRK2 levels in iPD subjects compared to healthy controls.…”

LRRK2 is recruited to phagosomes and co-recruits Rab8 and Rab10 in human pluripotent stem cell-derived macrophages

“…LRRK2 expression has also been linked with Mycobacterium tuberculosis infection (Härtlova et al, 2018;Wang et al, 2018). LRRK2 is expressed in a variety of cell lineages, including several immune subsets, notably B cells, neutrophils, monocytes, macrophages and microglia (Atashrazm et al, 2018;Fan et al, 2018;Gardet et al, 2010;Hakimi et al, 2011;Kim et al, 2012;Marker et al, 2012;Moehle et al, 2012;Thévenet et al, 2011) (reviewed in (Lee et al, 2017)).…”

Accurate MS-based Rab10 phosphorylation stoichiometry determination as readout for LRRK2 activity in Parkinson’s disease

“…We have recently identified a subset of Rab GTPases (Rab3A/B/C/D, Rab5A/B/C, Rab8A/B, Rab10, Rab12, Rab29, Rab35, and Rab43) as LRRK2 substrates 8,9 . Among these, Rab10 appears to be a key physiological kinase substrate [8][9][10][11][12][13][14] .…”