Background Juvenile Idiopathic Arthritis (JIA) is a collective term used to denote clinically discrete subtypes, which include: Enthesitis-related arthritis, Oligoarthritis, Polyarthritis, Psoriatic arthritis, Systemic arthritis and unclassified arthritis. Polyarthritis is further categorized according to rheumatoid factor (RF) status. The International League of Associations for Rheumatology (ILAR) has devised classification criteria of JIA with specific exclusion criteria and its diagnosis is reliant upon clinical symptoms. While laboratory tests like CBC, CRP, ESR, RF, ANA, and anti-CCP add prognostic value, they have limited utility for diagnosis. Thus, markers that can assist in sub-typing JIA at presentation are imperative as this can influence patient management strategy.
Objectives 14-3-3η is a joint derived, rheumatoid arthritis (RA) specific marker that informs radiographic damage. The purpose of this study was to examine the expression of 14-3-3η in the sub-types of JIA, and to assess whether a relationship existed between 14-3-3η and RF+ polyarthritis.
Methods 14-3-3η serum levels were measured in 60 JIA patients as shown in Table 1. One-way ANOVA analysis was used to determine if group differences existed. 14-3-3η positivity was defined using the adult RA diagnostic cut-off of ≥0.19 ng/ml. The Fisher's Exact test was employed to assess the relationship between RF and 14-3-3η positivity in polyarthritis patients.
Results ANOVA analysis revealed differences in 14-3-3η serum levels between the groups. Patients with RF positive polyarticular disease had significantly higher serum 14-3-3η levels than the other groups. 14-3-3η positivity analysis revealed that 30% of the oligoarthritis, 53% of RF negative polyarticular, 50% of psoriatic and 57% of patients with systemic arthritis were positive for 14-3-3η. Although there were only four patients in the enthesitis group, none of them were 14-3-3η positive. Fisher's Exact testing returned no significant association between RF and 14-3-3η positive status (p-value =0.35) indicating that the two markers may uniquely inform patient profiles within subtypes of JIA, especially since 53% of RF negative polyarticular JIA patients had positive 14-3-3η tests.
Conclusions 14-3-3η is a joint-derived mechanistic marker that up-regulates factors that are involved in joint damage pathogenesis. While RF+ polyarthritis patients had higher 14-3-3η levels, in JIA, 14-3-3η expression has no significant association with RF positivity and may provide insights into biochemical processes that uniquely inform JIA sub-typing.
Disclosure of Interest A. Rosenberg: None declared, W. Maksymowych Consultant for: Augurex Life Sciences Corp, (Co-inventor of 14-3-3η), Y. Gui Employee of: Augurex Life Sciences Corp, A. Marotta Employee of: Augurex Life Sciences, (Co-inventor of 14-3-3η)
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