Detection and discovery of autoantibodies as biomarkers in connective tissue disease

Abstract

Background and objectives
Autoantibodies are valuable diagnostic and prognostic biomarkers in connective tissue diseases, such as idiopathic inflammatory myopathy (IIM) and systemic sclerosis (SSc), where they are associated with specific clinical features including cancer and lung disease. I aimed to identify and characterise autoantibodies in juvenile IIM (JIIM), juvenile SSc (JSSc) and interstitial lung disease (ILD) patients using advanced discovery techniques, and to describe their prevalence and associated clinical presentation.

Methods
Patient sera were analysed by radio-immunoprecipitation (IP), known autoantibodies were identified, and unknown bands were characterised by mass spectrometry (MS). A small group of “autoantibody negative” juvenile myositis patients was analysed by gel-free IP-MS, bypassing the radio-IP and SDS-PAGE step. IP-blot, ELISA and immunofluorescence were used to identify and confirm autoantibody reactivity. Clinical presentation was described, and associations were analysed using appropriate statistical methods where possible.

Results
Several autoantibodies were identified for the first time in JIIM (anti-RCC1, FOXP1, ADAR1, TREX1, NKRF/XRN2/DHX15), JSSc (anti-RCC1 and SMARCA5) and ILD (anti-ANXA11) patients. Several autoantibody specific clinical associations were identified in JSSc patients. Several known autoantibodies previously missed by radio-IP were detected by MS, including anti-TIF1, anti-NXP2, anti-PM-Scl.

Conclusions
JIIM patients previously classified as “autoantibody negative” have identifiable autoantibodies, many of which target negative regulators of type 1 interferon. Functional studies are required to investigate their potential pathogenic role. Findings within the JSSc cohort confirm previously published associations between autoantibody specificity and SSc subtype and between anti-PM-Scl and ILD. A small percentage of patients diagnosed with idiopathic ILD have autoantibodies suggesting an autoimmune pathogenesis. This work highlights the use of IP-MS as an unbiased autoantibody discovery technique; further optimisation is required for its use as a diagnostic tool.

Date of Award	22 Apr 2026
Original language	English
Awarding Institution	University of Bath
Supervisor	Sarah Tansley (Supervisor), Neil McHugh (Supervisor) & Ian Eggleston (Supervisor)