AB1003 ANTI-DFS70 AUTOANTIBODIES, JUVENILE IDIOPATHIC ARTHRITIS (JIA) AND UVEITIS: ARE ANTI-DFS70 A PREDICTIVE MARKER OF UVEITIS RISK IN JIA PATIENTS?

Background: Juvenile idiopathic arthritis (JIA) is the most common paediatric rheumatic disease. Its most threatening complication is represented by uveitis, which could cause severe visual impairment if not diagnosed and treated promptly. It is an asymptomatic uveitis and the diagnosis is only instrumental. Therefore, regular ophthalmologic surveillance is crucial in the management of JIA. To date there are no specific predictive markers of uveitis development among JIA patients, including serologic subsets. Anti-Nuclear Antibodies (ANA) positive patients have the highest risk of iridocyclitis, but ANA are not specific. They could be found in patients with JIA without uveitis, in many other rheumatologic and inflammatory conditions and also in healthy subjects (6-12% of children). Anti-DFS70 antibodies (ANA forming a specific pattern in immunofluorescence) have been taken into consideration, but their role has not yet been established in a pediatric setting. Currently, there are few reports, involving small groups of patients and with non-univocal results. Some studies report anti-DFS70 antibodies more frequently in children with rheumatological diseases, in particular JIA-related uveitis; on the contrary, others describe them in healthy ANA positive patients. Objectives: 1) To evaluate the correlation between anti-DFS70 autoantibodies and the risk of developing uveitis in a cohort of patients with JIA ANA + in pediatric age; 2) to compare the prevalence of anti-DFS70 in patients with JIA, with a group of healthy ANA + children, to better define the role of these autoantibodies (potential risk factor or a protective factor for the development of AARDs in children?) Methods: We evaluated retrospectively 51 patients with JIA ANA +. We divided these patients in two groups, according to the presence (n=11) or the absence (n=40) of uveitis. For each patient we evaluated: gender, current age, age at diagnosis, type of JIA, therapy, presence of other diseases, dosage of ANA (with IF-Hep2), research of anti-ENA and anti-DFS70 antibodies (with chemiluminescence). Subsequently the whole group of patients with JIA was compared with a control group of healthy subjects aged ≤ 18 years (n=30), followed in the pediatric rheumatology clinic for occasional finding of ANA positivity, without pathologies at the moment of the study (in particular without rheumatological or autoimmune diseases). Results: Among patients with JIA without uveitis, anti-DFS70 autoantibodies were positive only in one patient. Anti-DFS70 were negative in all patients with JIA and uveitis. The difference between the two groups is not significant (p=1). In the group of healthy patients 6/30 (20%) presented a positivity of anti-DFS70 autoantibodies, in the absence of anti-ENA. Conclusion: Our data revealed no correlation between the positivity of anti-DFS70 autoantibodies and the risk of uveitis in patients with JIA ANA +, even if the number of patients is small. Further studies are needed to identify a reliable predictive marker of uveitis risk in JIA patients. The finding of a significant greater prevalence of anti-DFS70 autoantibodies in healthy ANA + subjects allows to suppose that this autoantibody could represent a possible protective marker for development of AARDs in asymptomatic children with isolated ANA positivity, as for adults. To confirm this hypothesis, it would be useful to carry on the study prospectively, encompassing children with other rheumatological diseases, and prolonging the clinical and laboratory follow up. References: [1]Clarke S, Sen ES, Ramanan AV. Juvenile idiopathic arthritis-associated uveitis. Ped Reumatol 2016; 14: 27. [2]Seeling CA, Bauer O, Seeling H-P. Autoantibodies Against DFS70/LEDGF Exclusion Markers for Systemic Autoimmune Rheumatic Diseases (SARD). Clin. Lab 2016;62:499- 517. [3]Schmeling H et al. Autoantibodies to Dense Fine Speckles in Pediatric Diseases and Controls. The Journal of Rheumatology 2015;42(12):2419-2426. Disclosure of Interests: None declared