Article

Chemerin activates fibroblast-like synoviocytes in patients with rheumatoid arthritis

Department of Medicine and Rheumatology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.
Arthritis research & therapy (Impact Factor: 4.12). 09/2011; 13(5):R158. DOI: 10.1186/ar3475
Source: PubMed

ABSTRACT Chemerin is a chemotactic agonist identified as a ligand for ChemR23 that is expressed on macrophages and dendritic cells (DCs). In this study, we analyzed the expression of chemerin and ChemR23 in the synovium of rheumatoid arthritis (RA) patients and the stimulatory effects of chemerin on fibroblast-like synoviocytes (FLSs) from RA patients.
Chemerin and ChemR23 expression in the RA synovium was ascertained by immunohistochemistry and Western blot analysis. Chemerin expression on cultured FLSs was analyzed by ELISA. ChemR23 expression on FLSs was determined by immunocytochemistry and Western blot analysis. Cytokine production from FLSs was measured by ELISA. FLS cell motility was evaluated by utilizing a scrape motility assay. We also examined the stimulating effect of chemerin on the phosphorylation of mitogen-activated protein kinase (MAPK), p44/42 mitogen-activated protein kinase (ERK1/2), p38MAPK, c-Jun N-terminal kinase (JNK)1/2 and Akt, as well as on the degradation of regulator of NF-κB (IκBα) in FLSs, by Western blot analysis.
Chemerin was expressed on endothelial cells and synovial lining and sublining cells. ChemR23 was expressed on macrophages, immature DCs and FLSs and a few mature DCs in the RA synovium. Chemerin and ChemR23 were highly expressed in the RA synovium compared with osteoarthritis. Chemerin and ChemR23 were expressed on unstimulated FLSs. TNF-α and IFN-γ upregulated chemerin production. Chemerin enhanced the production of IL-6, chemokine (C-C motif) ligand 2 and matrix metalloproteinase 3 by FLSs, as well as increasing FLS motility. The stimulatory effects of chemerin on FLSs were mediated by activation of ERK1/2, p38MAPK and Akt, but not by JNK1/2. Degradation of IκB in FLSs was not promoted by chemerin stimulation. Inhibition of the ERK1/2, p38MAPK and Akt signaling pathways significantly suppressed chemerin-induced IL-6 production. Moreover, blockade of the p38MAPK and Akt pathways, but not the ERK1/2 pathway, inhibited chemerin-enhanced cell motility.
The interaction of chemerin and ChemR23 may play an important role in the pathogenesis of RA through the activation of FLSs.

Download full-text

Full-text

Available from: Chie Miyabe, Jul 17, 2015
0 Followers
 · 
232 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chemerin stimulates migration of leukocytes to sites of inflammation and also increases inflammatory signaling in chondrocytes suggesting a function of chemerin in joint inflammation. Synovial fibroblasts (SF) are critically involved in synovitis and subsequent cartilage destruction. Here, we analyzed whether synovial fibroblasts express chemerin and its receptor CMKLR1. Further, the role of chemerin in synovial fibroblast chemotaxis, proliferation, insulin response and release of inflammatory proteins was studied. Synovial tissue sections were labeled with chemerin antibody and chemerin was measured in synovial fluid by ELISA. Chemerin mRNA and protein as well as CMKLR1 expression were determined in SFs from patients with osteoarthritis (OA) and rheumatoid arthritis (RA). Effects of chemerin on cytokines, chemokines and matrix metalloproteinases (MMP), and on proliferation, migration and insulin signaling were analyzed appropriately. SFs expressed CMKLR1 and chemerin mRNA, and chemerin protein was found in cell supernatants of synovial fibroblasts. Immunohistochemistry detected chemerin in synovial tissue predominantly localized within the lining layer. Chemerin was present in synovial fluids of RA, OA and psoriatic arthritis patients in similar concentrations. Chemerin neither increased IL-6 levels nor MMP-2 or -9 activity in SFs. Also, it did not act as a chemoattractant for these cells. With respect to intracellular signaling, neither basal nor insulin-mediated phosphorylation of Akt was affected. However, chemerin significantly increased TLR4 mRNA and synthesis of CCL2 in SFs while CCL4 and -5 were not altered. Cell proliferation of SFs, however, was modestly reduced by chemerin. These data show that human SFs express both chemerin and its receptor. As chemerin enhanced expression of TLR4 and induced release of CCL2 in SFs, a role of this protein in innate immune system-associated joint inflammation is proposed.
    Experimental and Molecular Pathology 02/2012; 92(1):90-6. DOI:10.1016/j.yexmp.2011.10.006 · 2.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: NKG2D is a stimulatory receptor expressed by natural killer (NK) cells, CD8(+) T-cells, and γδ T-cells. NKG2D expression is normally absent from CD4(+) T-cells, however recently a subset of NKG2D(+) CD4(+) T-cells has been found, which is specific for human cytomegalovirus (HCMV). This particular subset of HCMV-specific NKG2D(+) CD4(+) T-cells possesses effector-like functions, thus resembling the subsets of NKG2D(+) CD4(+) T-cells found in other chronic inflammations. However, the precise mechanism leading to NKG2D expression on HCMV-specific CD4(+) T-cells is currently not known. In this study we used genome-wide analysis of individual genes and gene set enrichment analysis (GSEA) to investigate the gene expression profile of NKG2D(+) CD4(+) T-cells, generated from HCMV-primed CD4(+) T-cells. We show that the HCMV-primed NKG2D(+) CD4(+) T-cells possess a higher differentiated phenotype than the NKG2D(-) CD4(+) T-cells, both at the gene expression profile and cytokine profile. The ability to express NKG2D at the cell surface was primarily determined by the activation or differentiation status of the CD4(+) T-cells and not by the antigen presenting cells. We observed a correlation between CD94 and NKG2D expression in the CD4(+) T-cells following HCMV stimulation. However, knock-down of CD94 did not affect NKG2D cell surface expression or signaling. In addition, we show that NKG2D is recycled at the cell surface of activated CD4(+) T-cells, whereas it is produced de novo in resting CD4(+) T-cells. These findings provide novel information about the gene expression profile of HCMV-primed NKG2D(+) CD4(+) T-cells, as well as the mechanisms regulating NKG2D cell surface expression.
    PLoS ONE 08/2012; 7(8):e41577. DOI:10.1371/journal.pone.0041577 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Resolvin E1 (RvE1) is a naturally occurring lipid-derived mediator generated during the resolution of inflammation. The anti-inflammatory effects of RvE1 have been demonstrated in a variety of disease settings; however, it is unknown whether RvE1 may also exert direct anti-fibrotic effects. We examined the potential anti-fibrotic actions of RvE1 in the mouse obstructed kidney - a model in which tissue fibrosis is driven by unilateral ureteric obstruction (UUO) - an irreversible, non-immune insult. Administration of RvE1 (300ng/day) to mice significantly reduced accumulation of α-smooth muscle actin (SMA)+ myofibroblasts and the deposition of collagen IV on day 6 after UUO. This protective effect was associated with a marked reduction of myofibroblast proliferation on days 2, 4 and 6 after UUO. RvE1 treatment also inhibited production of the major fibroblast mitogen, platelet-derived growth factor-BB (PDGF-BB), in the obstructed kidney. Acute resolvin treatment over days 2 to 4 after UUO also had a profound inhibitory effect upon myofibroblast proliferation without affecting the PDGF expression, suggesting a direct effect upon fibroblast proliferation. In vitro studies established that RvE1 can directly inhibit PDGF-BB-induced proliferation in primary mouse fibroblasts. RvE1 induced transient, but not sustained activation of the pro-proliferative ERK and AKT signalling pathways. Of note, RvE1 inhibited the sustained activation of ERK and AKT pathways seen in response to PDGF stimulation, thereby preventing up-regulation of molecules required for progression through the cell cycle (c-Myc, cyclin D) and down-regulation of inhibitors of cell cycle progression (p21 cip1). Finally, siRNA-based knock-down studies showed that the RvE1 receptor, ChemR23, is required for the anti-proliferative actions of RvE1 in cultured fibroblasts. In conclusion, this study demonstrates that RvE1 can inhibit fibroblast proliferation in vivo and in vitro, identifying RvE1 as a novel anti-fibrotic therapy. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
    The Journal of Pathology 10/2012; 228(4). DOI:10.1002/path.4050 · 7.33 Impact Factor
Show more