Interleukin (IL)-25 suppresses IL-22-induced osteoclastogenesis in rheumatoid arthritis via STAT3 and p38 MAPK/I\u03baB\u03b1 pathway

Hong Ki Min,Kyoung-Woon Kim,Sang-Heon Lee,Kyung-Ann Lee,Hae-Rim Kim,Seoung-Joon Lee,Ji-Yeon Won,Bo-Mi Kim

doi:10.1186/s13075-020-02315-8

Abstract

BackgroundThe present study aimed to evaluate the suppressive role of interleukin (IL)-25 in IL-22-induced osteoclastogenesis and receptor activator of nuclear factor κB ligand (RANKL) expression in rheumatoid arthritis (RA).MethodsSerum from patients with RA and osteoarthritis (OA), and healthy controls, and synovial fluid from patients with RA and OA were collected, and the levels of IL-22 and IL-25 were measured. RA and OA synovial tissues were stained against IL-25. Fibroblast-like synoviocytes (FLSs) of patients with RA were cultured with IL-22, in the presence or absence of IL-25, and RANKL expression was measured by real-time PCR and enzyme-linked immunosorbent assay (ELISA). Human peripheral blood monocytes were cultured under IL-22/RANKL + M-CSF, with or without IL-25, and tartrate-resistant acid phosphatase (TRAP)-positive cells and osteoclast-related markers were investigated to determine osteoclastogenesis.ResultsSerum and synovial IL-25 levels in RA were upregulated compared to those in OA and healthy control, and elevated expression of IL-25 in RA synovial tissue was re-confirmed. IL-25 and IL-22 levels showed significant correlation in serum and synovial fluid. Pre-treatment of FLS with IL-25 reduced IL-22-induced RANKL expression at the RNA level. The suppressive effects of IL-25 were confirmed to occur through the STAT3 and p38 MAPK/IκBα pathways. IL-25 reduced osteoclast differentiation and suppressed the expression of osteoclast-related markers.ConclusionIn the current study, we demonstrated the regulatory effect of IL-25 on IL-22-induced osteoclastogenesis. Therapeutic approach involving augmentation of IL-25 regulatory response may serve as a novel treatment option for RA, especially by suppressing osteoclastogenesis.

Highlights

The present study aimed to evaluate the suppressive role of interleukin (IL)-25 in IL-22-induced osteoclastogenesis and receptor activator of nuclear factor κB ligand (RANKL) expression in rheumatoid arthritis (RA)
Suppression of IL-22-mediated RANK ligand (RANKL) expression in fibroblast-like synoviocyte (FLS) after IL-25 pre-treatment Both mRNA and protein levels of RANKL in FLSs were measured by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively
Addition of IL-25 did not change mRNA levels of IL-22 receptors, IL-22R1 and IL-10RB (Fig. 2c), which indicates that suppressive role of IL-25 on RANKL expression was independent with expression levels of IL-22 receptor

Summary

Methods

Patients Samples of synovial tissue were isolated from 5 patients with RA (mean age 55.2 ± 3.8 years; range 44–64 years) and 5 with osteoarthritis (OA) patients (mean age 57.8 ± 3.0 years; range 50–68 years), who were undergoing total knee replacement surgery. After blocking with phosphate-buffered saline/1% bovine serum albumin (BSA)/0.05% Tween 20 for 2 h at room temperature (22–25 °C), the test samples and the standard recombinant IL-22, IL-25, IL-1β, TNF-α, IL-6, IL-4, IL-13, and sRANKL (R&D Systems) were added to the 96-well plate and incubated at room temperature for The plates were washed four times with phosphate-buffered saline/Tween 20, and incubated with 500 ng/ml biotinylated mouse monoclonal antibodies against IL-22, IL-25, IL-1β, TNF-α, IL-6, IL-4, IL13, and sRANKL (R&D Systems) for 2 h at room temperature.

Results

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Discussion

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