Engineering antibodies for diagnostic and therapeutic approaches in neurodegenerative diseases
Authors: Najjar Ahmad 
Published: June 2019

Engineering antibodies for diagnostic and therapeutic approaches in neurodegenerative diseasesA. Najjar1, N.N. Vaikath2, I, Hmila2, Nour Majbour2, O. El-Agnaf11Life Sciences Division, College of Science and Engineering, Hamad Bin Khalifa University (HBKU), Education City, Qatar Foundation, PO Box 5825, Doha, Qatar2Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, PO Box 5825, Doha, Qatar.Neurodegenerative diseases affect millions of people worldwide, with Parkinson’s disease (PD) ranked as the second most common age-related neurodegenerative disorder affecting over 1 million people in the United States alone. Common neurodegenerative diseases such as PD, Dementia with Lewy Bodies (DLB) and Multiple System Atrophy (MSA) are characterised by progressive deposition of α-synuclein (α-syn) protein within inclusions referred to as Lewy bodies and glial cytoplasmic inclusions respectively. This has led to classifying these diseases under the umbrella term Synucleinopathies due to the pathological accumulation of this protein. The various diseases vary in where the protein is deposited and which regions in the brain become affected.α-Syn is a relatively small protein constituting 140 amino acid residues having an unfolded native state. α-Syn aggregation occurs in a stepwise manner where monomers lead to transient oligomers, which ultimately lead to proto and mature fibrils within neurons. Such accumulation seems to target dopaminergic neurons located in the substantia nigra pars compacta. Current treatment such as Deep Brain Stimulation (DBS) and L-dopa (the precursor for dopamine) does not focus on slowing disease progression; rather it focuses on symptomatic relief.Amongst the various approaches attempting to tackle the pathological features of synucleinopathies, immunotherapy holds much promise. α-Syn antibodies could potentially block processes leading to the pathogenesis of such neurodegenerative diseases. The limitation of such antibodies is their inefficiency in crossing the Blood-Brain Barrier. The aim of our project focuses on using a fusion protein engineered to include the FAB region of an existing antibody, which is confirmation specific to α-syn pathology. This single-chain-fragment-variable is designed to have increased BBB penetration by virtue of its smaller size and its conjugation with a carrier. It is envisaged that with enhanced penetration there will be superior brain targeting results compared to conventional α-syn antibodies. Upon expression and purification of α-syn and various designs of the fusion protein, the two proteins will be extensively characterized by means of Dot Blots, ELISA assays and affinity experiments. Neuronal cell lines and primary neurons from rat or mice will be employed to test our fusion protein in vitro. This will ultimately be done using immunocytochemistry techniques. For in-vivo experiments, the fusion protein will be tested on transgenic mice overexpressing α-syn.The outcomes of this project are threefold. If successful, the fusion protein could be useful in passive immunization of Synucleinopathies, finding its use as a clinical diagnostic tool for such diseases. Further manipulation of the fusion protein, namely attachment of a Fluoro-radiolabelled isotope can be used for imaging using positron emission tomography (PET). This would allow for its use in medical imaging to track α-syn pathology in PD, DLB and MSA patients.