Neutrophil-Derived Lactoferrin Regulates the Activity of NFAT5 in Rheumatoid Arthritis Synovial Fibroblasts Via Toll-like Receptor 4

Kunihiko Umekita, Shunichi Miyauchi, Kazuyoshi Kubo, Hajime Nomura, Kazumi Umeki, Koushou Iwao, Mao Komura and Akihiko Okayama, Department of Rheumatology, Infectious Diseases and Laboratory Medicine, University of Miyazaki, Miyazaki, Japan

Meeting: 2015 ACR/ARHP Annual Meeting

Date of first publication: September 29, 2015

Keywords: innate immunity, neutrophils, pathogenesis and toll-like receptors, rheumatoid arthritis

Session Information

Date: Tuesday, November 10, 2015

Title: Rheumatoid Arthritis - Human Etiology and Pathogenesis Poster III

Session Type: ACR Poster Session C

Session Time: 9:00AM-11:00AM

Background/Purpose: Damage-associated molecular patterns (DAMPs) are proposed to drive aberrant stimulation of Toll-like receptors (TLRs) in the rheumatoid arthritis (RA) joints resulting in increased expression of proinflammatory cytokines and chemokines. In the current study we investigated the role of the neutrophil-derived lactoferrin (LTF), as an endogenous ligand for TLR4 in the inflammatory response of RA synovial fibroblasts (RASF).

Methods: Recombinant human neutrophil-derived LTF was purchased from Sigma. LTF solution was screened for lipopolysaccharide contamination before using. RASF were treated with LTF and/or TNFα, and the expression of proinflammatory cytokines in RASF was measured by real-time quantitative PCR and multi-cytokine assay system. The levels of phosphorylated p38 mitogen associated phosphokinase (MAPK) in RASF stimulated with LTF were determined by immune blotting. To repress the TLR4 signaling pathway, TAK243, a small molecular inhibitor of TLR4, was used. The role of the nuclear factor of activated T cells 5 (NFAT5) in the TLR4 signaling pathway in RASF was investigated using a small interfering RNA targeting NFAT5.

Results: Stimulation of RASF with LTF significantly increased the mRNA and protein expression of proinflammatory cytokines, such as IL-6, IL-8 and CCL20 (p=0.01). Furthermore, LTF enhanced the expression of IL-6, IL-8, and CCL20 mRNA in RASF stimulated by TNFα (p=0.01). The phosphorylation of p38MAPK increased in LTF-stimulated RASF. TAK243, the TLR4 inhibitor, repressed the expression of proinflammatory cytokines and chemokines in RASF stimulated by LTF. Silencing of NFAT5 significantly decreased the expression of proinflammatory cytokines and chemokines in RASF treated by LTF (p= 0.01).

Conclusion: This is the first study to demonstrate that LTF can induce the proinflammatory response in RASF mediated by TLR4 and the activation of NFAT5. Neutrophil derived LTF is is an endogenous ligand for TLR4 in RASF. The activity of NFAT5 is important in the inflammatory response of RASF induced by LTF via TLR4.

Disclosure: K. Umekita, None; S. Miyauchi, None; K. Kubo, None; H. Nomura, None; K. Umeki, None; K. Iwao, None; M. Komura, None; A. Okayama, None.

To cite this abstract in AMA style:

Umekita K, Miyauchi S, Kubo K, Nomura H, Umeki K, Iwao K, Komura M, Okayama A. Neutrophil-Derived Lactoferrin Regulates the Activity of NFAT5 in Rheumatoid Arthritis Synovial Fibroblasts Via Toll-like Receptor 4 [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/neutrophil-derived-lactoferrin-regulates-the-activity-of-nfat5-in-rheumatoid-arthritis-synovial-fibroblasts-via-toll-like-receptor-4/. Accessed .

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