Volume 35, Issue 1, March 2024

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Mediterr J Rheumatol 2024;35(1):134-42
A Study on the Immunoregulatory Role of the PD1 Pathway in Juvenile Idiopathic Arthritis
Authors Information

First Department of Paediatrics, Hippokration General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece

A Koutsonikoli, A Taparkou, P Pratsidou-Gertsi, V Sgouropoulou, M Trachana


Objectives: To investigate the immunoregulatory role of the Programmed-cell-Death-protein-1 (PD1) pathway, an inhibitory immune checkpoint, in Juvenile Idiopathic Arthritis (JIA). Methods: The PD1 expression on CD4+ and CD8+ T-cells was determined by flow cytometry and the PD1 soluble form (sPD1) levels by ELISA, in peripheral blood (PB)/serum and synovial fluid (SF) samples of JIA patients and healthy controls (HCs). We searched for any association in-between the biomarkers and with JIA activity. Results: 101 Caucasian patients (69 female), aged 12 (8-15) years, and 20 HCs participated in this study. The PB PD1 expression on T-cells was higher in: a. JIA patients vs HCs (CD4: 1.24% vs 0.32%, p=0.007, CD8: 1.6% vs 0.4%, p=0.002). b. active vs inactive JIA (CD4: 1.44% vs 0.87%, p=0.072, CD8: 2.1% vs 0.93%, p=0.005). The SF PD1 expression on T-cells correlated strongly and positively with the disease activity (CD4: ρ=0.55, p=0.022, CD8: ρ=0.555, p=0.026). The SF PD1 expression on CD8 T-cells was higher in patients on-treatment vs those off-treatment (21.3% vs 5.83% p=0.004). The sPD1 levels were higher in the SF vs the serum (801pg/ml vs 367.2, p=0.013), without an association with disease activity. Conclusion: These results indicate an up-regulation of the PD1-pathway in JIA, at least quantitatively, especially in active disease. sPD1 is compartmentally produced at the inflamed joints. Further investigation in a larger sample of JIA patients may verify these observations and contribute to unravelling the precise role of the PD1 pathway in the pathogenesis and persistence of the joint inflammation.


Cite this article as: Koutsonikoli A, Taparkou A, Pratsidou-Gertsi P, Sgouropoulou V, Trachana M. A Study on the Immunoregulatory Role of the PD1 Pathway in Juvenile Idiopathic Arthritis. Mediterr J Rheumatol 2024;35(1):134-42.

Article Submitted: 14 May 2023; Revised Form: 19 Jul 2023; Article Accepted: 20 Jul 2023; Available Online: 29 Aug 2023

This work is licensed under a Creative Commons Attribution 4.0 International License.

©2024 The Author(s).