Recent studies indicate the potential use of LRRK2 or LRRK2 phosphorylation (protein regulation) in biosamples as disease markers or as markers of response to novel therapeutics targeting LRRK2. LRRK2 is expressed in the brain as well as in the cerebrospinal fluid (baths the brain and spinal cord). Reports show increases in LRRK2 protein levels in those with Parkinson's disease (PD), suggesting that increases in total LRRK2 protein expression are associated with the disease. Furthermore, LRRK2 phosphorylation is regulated in several disease mutant forms of LRRK2. In the S910-S935-S955-S973 phosphosites (sites on a protein), levels are reduced, while for phospho-S1292, levels are increased for several disease mutants; these five LRRK2 phosphosites are also rapidly dephosphorylated (deactivated) upon LRRK2 inhibitor treatment and are thus considered potential therapeutics.
This study seeks to develop methods to reliably and quantifiably detect low quantities of LRRK2 and phospho-LRRK2 in cerebrospinal fluid, for use as markers for both disease progression as well as drug response.
As test material to set up assays, LRRK2 recombinant protein will be generated and diluted in artificial cerebrospinal fluid (aCSF). Immuno-PCR (DNA measurement) techniques will be set up to detect several LRRK2 epitopes (sites on a molecule) and detection limits will be determined from recombinant LRRK2 in aCSF. Phospho-mutant forms of LRRK2 will be used as controls. The study will pursue detection assays (tests) with sufficient sensitivity for LRRK2 or phospho-LRRK2. Given the complexity of CSF composition and the potential differences in accessibility to antibodies (immune system proteins) in CSF, several protocols will be tested both in total CSF as well as in CSF exosomes (storage packets in body fluids).
Impact on Diagnosis/Treatment of Parkinson's Disease:
CSF dosing has shown its utility in diagnosis and as a marker in clinical trials for several diseases, such as in Alzheimer's disease (dosing of Aβ and tau). Our study will develop LRRK2 detection assays for CSF that can directly be implemented in clinical trials, as biomarkers of both drug response as well as of disease progression for Parkinson's.
Next Steps for Development:
The assays set up in this project can be further developed to apply to other clinical biosamples, such as blood, serum, urine and tissue extracts, for use in drug testing in cell cultures as well as for use in pre-clinical models of Parkinson's.