Identification of novel antibodies predictive of the development of uveitis in jia using high-density nucleic acid programmable protein arrays

Introduction: Currently all children with oligo and polyarticular JIA have to be screened by ophthalmologists for years in order to ensure that this completely asymptomatic disease is not missed. If missed or inadequately treated, some 50% of these children can go functionally blind. The only useful biological marker currently available is ANA status. However this is neither sensitive nor specific enough to significantly alter regular clinical screening. It does however suggest that autoantibodies, as yet undiscovered, may be important in the pathophysiology of this disease.
We undertook this proof of concept study to see whether a novel technique capable of producing multiple proteins could be used to screen for autoantibodies that are associated with uveitis development in JIA patients. This could enable us to identify children, at the time of diagnosis of arthritis, who are highly likely to develop uveitis.

Objectives: To Identify novel antibodies that predict the development of uveitis in children with JIA.

Methods: Nucleic Acid Programmable Protein Arrays (NAPPA) enable the in situ production of multiple proteins from DNA templates which are immobilised on a solid phase. Methodology is described in detail elsewhere [1]. NAPPA slides with 2200 genes were produced. Pubmed search identified ~60 genes associated with uveitis pathology and ~30 genes associated with arthritis development. The remaining ~2100 genes were randomly identified from a ~12000 human gene collection (http://dnasu.asu.edu). The arrays were then probed using plasma from JIA patients with (n = 20) and without uveitis (n = 20) and from healthy age and sex matched controls (n = 20). Proteins with higher levels of antibody detected were confirmed by ELISA.

Results: NAPPA image analysis revealed distinct signals from plasma antibodies of JIA patients with Uveitis which had reacted with specific array proteins. Hierarchical clustering heat maps were used to visualize clusters of proteins with higher array reactivity for JIA or Uveitis samples, realtive to controls. ELISA's were developed for nine highly reactive proteins including BATF, FO5, PROSAPIP1, CCND1, NOUFV3 and SSB. Antibodies specific for single-stranded DNA-binding proteins (SSB) were confirmed to be at significantly higher concentrations in the plasma of JIA patients with uveitis, relative to JIA patients without eye disease.

Conclusion: These results indicate that the NAPPA technique is a sensitive tool for screening antigens including specific nuclear antigens which distinguish JIA patients with uveitis. We plan on developing a nuclear antigen array with over 2000 features to determine further uveitis patient reactivity. Prospective studies are also required to establish if these immunoglubulins are present at detectable levels in JIA patients prior to development of uveitis and to assess their predictive utility.