Background Enthesitis-related arthritis (ERA) is a category of juvenile idiopathic arthritis. Different proinflammatory cytokines linked to the Th1 and Th17 T- cell subsets have been implicated in its pathogenesis. Limited data are currently available about the relationship between disease activity and the clinical pattern and the percentage of Th1and Th17 T- cell subsets.

Objectives To analyze Th1 and Th17 cell subsets in patients with ERA and to compare with age-matched healthy controls. To assess the association between disease activity and disease clinical pattern with Th1and Th17 cells subsets

Methods Patients with ERA (according to ILAR criteria) were included in a cross sectional study. Disease activity measures were collected in random visits: active joint count (AJ), pain score (0–10), presence of active enthesitis (AE), sacroiliac pain (SIP), lumbar pain (LP),lumbar limitation (LL) by Schöber's test, wellbeing according to the patient using a visual analogue scale (VASp, 0–10), disease activity according to the physician (VASphy, 0–10), JADAS-10, JSpADA, and ESR/CRP were evaluated. Patients were classified based on the disease pattern (peripheral and non-peripheral) depending on the presence or absence of AJ and/or AE. Functional capacity was also assessed by CHAQ. Presence of radiologic sacroiliitis (MRI/X-rays) and treatment with TNF inhibitors (TNFi) were recorded. Th-17 and Th-1 cells were quantified by flow cytometry in PBMCs stimulated with PMA/IO. Age-matched healthy children without disease or medication were recruited as normal control. Comparison between groups (Mann-Whitney Utest) and correlation tests as appropiate

Results Twenty-nine patients (90% M) fulfilled inclusion criteria. HLA-B27 was positive in 13 (45%). Median age at observation was 12 years and median disease duration was 2.1 years. Activity and functional measures were (medians): AJ 1, pain 0.25, VASp 0.5, VASphy 1, JADAS-10 7, JSpADA 1.75, ESR 15 mm/h, and CHAQ ≥0,5=8 patients (27%). AE was present in 1 (3%), SIP in 7 (24%), LP in 6 (21%), and LL in 12 (41%) children. Nineteen (65%) patients showed JADAS >1 and 21 (76%) JSpADA>0. Radiologic sacroilitis was recorded in 21 (72%) children. Fourteen (48%) patients were treated with TNFi. Th1cell percentage in ERA was 8.5±3.4% (range, 4–17.4) while healthy controls was 5.8±3.8% (range, 1.2–14.2), p=0.023. Th17cell% in ERA was 0.90±0.44 (range, 0.39–2.34%) while controls was 0,55±0.38 (range, 0,17–1,61%); p=0.004. There was no difference between T-cells% and active/inactive disease. Eighteen (62%) children showed peripheral pattern, while 11 (38%) exhibited non-peripheral. Peripheral and non-peripheral groups showed Th17%cells 0.90 (0.39–1.74) vs 1.14 (0.64–2.44) respectively (p=0.018).Significant correlations were Th1 with AJ (r=0.45 p=0.004) and Th17with LP (r=0.83 p=0,0001), LL (r=0.47 p=0.03).

Conclusions Th1 and Th17 cells subsets were significantly higher in ERA compared with healthy controls. However, T-cells showed no significant difference between patients with active versus inactive disease. Interestingly, non-peripheral pattern showed higher Th17% cells respect to patients with peripheral disease.Our results suggest that Th17 evaluation could help identify different phenotypes that benefit from Th-17 blocking strategies.

References

1. Biologic agents in juvenile spondyloarthropathies. Katsicas MM, Russo R. Pediatr Rheumatol Online J.2016Mar 12;14 (1):17.

References

Disclosure of Interest None declared