Higher Synovial Immunohistochemistry Reactivity of IL-17A, Dkk1, and TGF-β1 in Patients with Early Psoriatic Arthritis and Rheumatoid Arthritis Could Predict the Use of Biologics

Abstract

Background: Delay in diagnosis and therapy in patients with arthritis commonly leads to progressive articular damage. The study aimed to investigate the immunohistochemical reactivity of synovial cytokines associated with inflammation and the bone erosives/neoformatives processes among individuals diagnosed with psoriatic arthritis (PsA), rheumatoid arthritis (RA), osteoarthritis (OA), and radiographic axial spondyloarthritis (r-axSpA), with the intention of identifying potential biomarkers.

Methods: Specimens were collected from the inflamed knee joints of patients referred for arthroscopic procedures, and the synovial tissue (ST) was prepared for quantifying protein expression through immunohistochemical analysis (% expressed in Ratio_Area-Intensity) for TGF-β1, IL-17A, Dkk1, BMP2, BMP4, and Wnt5b. The collected data underwent thorough analysis and examination of their predictive capabilities utilising receiver operating characteristic (ROC) curves.

Results: Valid synovial tissue samples were acquired from 40 patients for IHC quantification analysis. Initially, these patients had not undergone treatment with biologics. However, after 5 years, 4 out of 13 patients diagnosed with PsA and two out of nine patients diagnosed with RA had commenced biologic treatments. Individuals with early PsA who received subsequent biologic treatment exhibited significantly elevated IHC reactivity in ST for TGF-β1 (p = 0.015). Additionally, patients with both PsA and RA who underwent biologic therapy displayed increased IHC reactivity for IL-17A (p = 0.016), TGF-β1 (p = 0.009), and Dkk1 (p = 0.042). ROC curve analysis of IHC reactivity for TGF-β1, Dkk1, and IL-17A in the synovial seems to predict future treatment with biologics in the next 5 years with the area under the curve (AUC) of a combined sum of the three values: AUC: 0.828 (95% CI: 0.689-0.968; p 0.005) S 75% E 84.4%.

Conclusions: Higher synovial immunohistochemistry reactivity of IL-17A, Dkk1, and TGF-β1 in patients with early psoriatic arthritis and rheumatoid arthritis may serve as potential indicators for predicting the necessity of utilising biologic treatments.

Keywords: Dkk1; IHC reactivity; IL-17A; TGF-β1; biomarker; psoriatic arthritis; synovial tissue.

Figure 1

Differences in baseline IHC expression levels of Dkk1, TGFβ1, and IL-17A in the synovial tissue, whether biologics were required or not. Synovial tissue IHC expression of the 3 cytokines (IL-17A, TGF-β1, and Dkk1) in all patients (PsA, RA, OA, and r-axSpA) is shown divided into 2 groups: those who have received biological treatment and those who have not received biological treatment.

Figure 2

Boxplots of IHC reactivity in the early synovial tissue in the 3 groups: Controls, PsA/RA treated with biologics, and PsA/RA patients treated without biologics. Controls: osteoarthritis and axial spondylarthritis patients. The y scale represents the relative intensity percentage of IHC reactivity. Numbers in the graphs represent the identification code of patients with extreme IHC quantification values. Pairwise statistical significance was obtained by the Dunn–Bonferroni test when the Kruskal–Wallis test was calculated. The IHC expression ratio is significantly higher in the PsA/RA group treated with biologics for Dkk1 (A), IL-17A (B), and TGF-β1 (C) compared to the control group and the PsA/RA group treated without biologics. In the case of Wnt5b (D), BMP2 (E), and BMP4 (F), IHC expression is also higher in the PsA/RA group treated with biologics compared to the control group but does not reach statistical significance in the case of BMP4.

Figure 3

ROC curve analysis of IHC reactivity for TGF-β1, Dkk1, and IL-17A in the synovial tissue. ROC: Receiver-operating characteristic curve analysis of synovial tissue.

Figure 4

ROC curve analysis of IHC reactivity combined sum for TGF-β1, Dkk1, and IL-17A in the synovial tissue. ROC: Receiver-operating characteristic curve analysis of synovial tissue. Score with a combined sum of the 3 values: AUC: 0.828 (95% CI: 0.689–0.968; p = 0.005) S 75% E 84.4%. Cutoff value of IHC combined sum = 90. Youden’s Index: 0.59.

Figure 5

Immunohistochemical expression of TGFβ1, IL-17A, and DKK1 in the synovial tissue of patients treated with and without biologics while affected by their disease. Representative images of synovial tissue of swollen knee from each group of study. Synovium sections were analysed by immunohistochemistry (brown) for TGFβ1, IL-17A, and Dkk1, expressed in the synovial from: (A) PsA treated with biologics; (B) RA treated with biologics; (C) PsA treated without biologics; (D) Controls (OA/axSpA). All tissues were counterstained with haematoxylin from each group of study (original magnification 20×, 100×).