Journal
CELLS
Volume 9, Issue 4, Pages -Publisher
MDPI
DOI: 10.3390/cells9040938
Keywords
rheumatoid arthritis; interleukin-26; macrophage differentiation
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Funding
- Ministry of Science and Technology, Taiwan, Republic of China [MOST 105-2320-B-016-002, 107-2314-B-016-066-MY3]
- Ministry of National Defense Medical Affairs Bureau [MAB-107-030]
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Interleukin 26 (IL-26) is a new member of the IL-10 family that is highly expressed in rheumatoid arthritis (RA). However, the functions of IL-26 produced by macrophages in RA have not been elucidated. In the present work, we evaluated the effects and the mechanisms of IL-26 on M1 and M2 macrophage differentiation. Human or mouse macrophage cells were treated with lipopolysaccharides (LPS), interferon gamma (IFN gamma), or IL-4 alone or concurrently treated with IL-26 to monitor M1 or M2 macrophage subtypes. The expression level of M1 or M2 macrophage genes was evaluated by reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The molecular mechanisms of downstream signaling activation during differentiation were investigated by immunoblotting assay. Our results found that IL-26 promoted macrophage cells from CD80(+) M1 macrophage differentiation, not from the CD206(+) M2 phenotype. The messenger RNA of M1-type macrophage markers tumor necrosis factor alpha (TNF alpha) and inducible nitric oxide synthase (iNOS) was up-regulated in the IL-26-treated group. Also, the M1-related proinflammatory cytokines TNF alpha and IL-6 were induced after IL-26 stimulation. Interestingly, IL-10, a cytokine marker of M2 macrophage, was also elevated after IL-26 stimulation. Moreover, the M1-like macrophage stimulated by IL-26 underwent cJUN, nuclear factor kappa B (NF-kappa B), and signal transducer and activator of transcription 1 (STAT1) activation. Our findings suggested the role of IL-26 in synovial macrophages of active rheumatoid arthritis and provided a new insight into IL-26 as a candidate therapeutic target in rheumatoid arthritis.
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