Background/Purpose: 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.
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. 

Conclusion: 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.