Autoantibody Sensing for early diagnosis of rheumatic diseases.

Abstract

Rheumatic diseases directly affect approximately 1.5 million people in the UK. Improving the early detection of rheumatic diseases would allow for more focused and aggressive treatment to reduce short term suffering and slow down progression to longer term complications. Rheumatic diseases are autoimmune diseases in which autoantibodies target an individual’s own proteins. Autoantibodies can be used as markers for rheumatic diseases, so an array-based electrochemical sensor for the detection of autoantibodies would allow for early detection of rheumatic diseases. A sensor comprised of an array of autoantigens on a surface would use those autoantigens as bait to detect autoantibodies in blood. This research investigates the design of an electrochemical biosensor based on this concept: fragments of myositis autoantigens have been immobilised on a gold surface for the detection of autoantibodies. The aim is to develop a biosensor that allows fast and early diagnosis of multiple rheumatic diseases.

Fragments of myositis autoantigens Jo-1, TRIM21 and TRIM33 have been cloned, expressed using E. coli and purified using immobilised metal ion affinity chromatography. Autoantigen fragments were immobilised on a gold electrode using gold-sulphur covalent bonding enabled by introduction of a non-native terminal cysteine. After some optimisation studies, these gold-autoantigen assemblies were tested for detection of autoantibodies using commercial antibody controls to generate antibody concentration calibration curves. Clear trends between antibody concentration and charge transfer resistance, as measured by electrical impedance spectroscopy, were observed, indicating the ability of the sensors to detect their target antibody. With the calibration curves as a guideline, each autoantibody biosensor was used to detect the presence of autoantibodies in patient samples with known autoantibody status. The results obtained provide proof of principle that electrical impedance spectroscopy-based biosensors can be developed to detect autoantibodies in myositis patient samples, using antigen-modified electrodes to capture target autoantibodies.

Future work may involve optimisation to allow quantitative measurement of autoantibodies, plus combining individual myositis autoantibody sensors into a multiplex sensor. This would allow rapid, quantitative screening of patient samples to detect myositis autoantibodies and provide diagnostic and prognostic information.

Date of Award	12 Dec 2022
Original language	English
Awarding Institution	University of Bath
Supervisor	Stefan Bagby (Supervisor), Pedro Estrela (Supervisor), Neil McHugh (Supervisor) & Paul Winyard (Supervisor)