Activin A Expressed in Rheumatoid Synovial Cells Downregulates TNFα-Induced CXCL10 Expression and Osteoclastogenesis

Abstract

Objective: Activin A is known to be highly expressed in rheumatoid synovium. In the present study, we investigated the effect of inflammatory cytokines on activin A production and its role in rheumatoid inflammation using freshly prepared rheumatoid synovial cells (fresh-RSC). Methods: Fresh-RSC from patients with rheumatoid arthritis were obtained and stimulated with multiple cytokines for activin A production. Gene expression levels of activin A and inflammatory cytokines were determined by quantitative PCR (qPCR) analysis. An enzyme-linked immunosorbent assay (ELISA) was used to measure activin A and CXCL10 in culture supernatants. The osteoclasts generated from human peripheral monocytes by RANKL stimulation were identified by tartrate-resistant acid phosphatase staining and bone resorption assay using Osteo plate. The expression levels of NFATc1 and cathepsin K, critical intracellular proteins for osteoclastogenesis, were determined by Western blotting. Results: Activin A production in fresh-RSC was markedly enhanced by the synergistic effect of TGF-β₁ with inflammatory cytokines, including TNFα, IL-1β, and IL-6. Activin A inhibited TNFα-induced CXCL10, an important chemoattractant for pathogen-activated T cells and monocytes of osteoclast precursors, but it did not affect the expression of inflammatory cytokines and chemokines. In addition, activin A directly inhibited the expression of NFATc1 and cathepsin K, as well as osteoclast formation in human samples. Conclusion: Our data indicated that TGF-β₁ is involved in the expression of activin A at inflamed joints. Activin A mainly exerts an anti-inflammatory action, which prevents joint damage via the regulation of CXCL10 and osteoclastogenesis.

N1-methylpseudouridine-incorporated mRNA enhances exogenous protein expression and suppresses immunogenicity in primary human fibroblast-like synoviocytes

“…Inflammation exacerbates the pathophysiology of joint diseases, and human RA-derived FLS reportedly produce high levels of IL-6 and CXCL10 (Bartok and Firestein 2010;Kuranobu et al 2020;Yukawa et al 2020). Therefore, it is desirable that IVT mRNA has low immunogenicity when developing a therapeutic strategy involving gene replacement for arthritis.…”

N1-methylpseudouridine-incorporated mRNA enhances exogenous protein expression and suppresses immunogenicity in primary human fibroblast-like synoviocytes

“…Inflammation exacerbates the pathophysiology of joint diseases, and human RA-derived FLS reportedly produce high levels of IL-6 and CXCL10 [37][38][39] . Therefore, it is desirable that IVT mRNA has low immunogenicity when developing a therapeutic strategy involving gene replacement for arthritis.…”

The Lipopolysaccharide Mutant Re-LPS Is a Useful Tool for Detecting LPS Contamination in Rheumatoid Synovial Cell Cultures

“…All patients were treated with prednisolone and DMARDs (1 patient received bucillamine/tacrolimus, one received tocilizumab, one received bucillamine/actarit, and one received leflunomide/iguratimod/etanercept). RSCs were isolated by enzymatic digestion of the synovial tissues, as described previously [10]. In brief, isolated rheumatoid synovia was aseptically dissected from surrounding tissues, minced, and enzymatically digested with 1–2 mg/mL Clostridium collagenase (Wako Pure Chemical Industries) and 5–10 μg/mL deoxyribonuclease 1 (Sigma-Aldrich) for 2–3 h at 37°C.…”