oa Development of Novel Diagnostic and Therapeutic Tools for Parkinson's Diseases and Related Disorders

Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease. The biggest roadblock we are facing for the cure of PD is the lack of reliable biomarkers for the disease diagnosis or progression. This is a problem, not only from a clinical standpoint, but also because it affects the integrity of clinical trials and epidemiological research. Thus, the development of simple diagnostic tests to aid the clinical diagnosis of PD and other neurodegenerative diseases is of great importance. PD is characterized with a long preclinical phase that might serve as a window for early therapeutic intervention once disease-modifying therapies are available, however, the lack of reliable biomarkers for PD diagnosis and progression represents a major obstacle to achievement of this goal. One of the most prominent pathological features of most neurodegenerative diseases is the deposition of specific protein aggregates in neuronal or glia cells. In PD, such deposits are named Lewy bodies (LBs) and Lewy neuritis (LNs), the pathological hallmarks of PD, in which α-syn is the main constituent. α-Syn is 140 amino acid, a pre-synaptic neuronal protein and its aggregation and dysfunction is linked to a number of neurodegenerative disorders, named Synucleinopathies. PD, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA) all fall under the umbrella of Synucleinopathies. The aggregation of α-syn starts long before the onset of the clinical symptoms and continues to spread throughout the brain as the disease progresses, making these aggregates strong candidates for biomarkers development. α-Syn is subjected to several post-translational modifications (PTMs) such as phosphorylation, oxidation, nitrosylation, truncation and ubiquitination. However, whether these PTMs act to enhance or halt α-syn neurotoxicity remains poorly understood. Biochemical examination of LBs revealed the presence of full-length α-syn as well as different species of truncated α-syn. Truncated α-syn was found in the brains of patients as well as the brains of healthy subjects, suggesting that α-syn truncation takes place even under normal physiological conditions. A marked difference, however, in the amount of truncated α-syn in synucleinopathies’ patients was noted compared to control subjects. Truncated α-syn was also found to be abundant in the brains of PD and DLB patients, suggesting that truncated α-syn may play a normal physiological role as well as a pathological one. Our group has succeeded to develop several highly specific antibodies that were explored for diagnostic and therapeutic purposes. Here in this project, we describe the characterization and applications of our novel conformation-specific mouse monoclonal antibodies against different truncations of α-syn as diagnostic and therapeutic tools for synucleinopathies. The specificity and sensitivity of our antibodies were thoroughly assessed by an array of biochemical methods including slot blotting, western blotting, ELISA and immunohistochemical analysis in parallel with commercially available antibodies. Next, we explored the potential of these novel tools in biological samples (brain tissues and biofluids) from patients with different synucleinopathies. Our antibodies exhibited a specificity towards different conformations of α-syn that none of their commercial peers did. Our novel antibodies also stained a pathology in human brain tissues that was not captured by gold standard antibodies for Immunostaining of α-syn pathologies. Our antibodies are not only valuable for the discovery of ideal biomarkers but also for a better understanding of the underlying pathophysiological process in PD and related disorders.