Notch Signaling Mediates TNF-α-Induced IL-6 Production in Cultured Fibroblast-Like Synoviocytes from Rheumatoid Arthritis

Abstract

It has been reported that Notch family proteins are expressed in synovium tissue and involved in the proliferation of synoviocyte from rheumatoid arthritis (RA). The aim of this paper was to investigate whether Notch signaling mediated TNF-α-induced cytokine production of cultured fibroblast-like synoviocytes (FLSs) from RA. Exposure of RA FLSs to TNF-α (10 ng/ml) led to increase of Hes-1, a target gene of Notch signaling, and a marked upregulation of Notch 2, Delta-like 1, and Delta-like 3 mRNA levels. Blockage of Notch signaling by a γ-secretase inhibitor (DAPT) inhibited IL-6 secretion of RA FLSs in response to TNF-α while treatment with recombinant fusion protein of Notch ligand Delta-like 1 promoted such response. TNF-α stimulation also induced IL-6 secretion in OA FLSs; however, the Hes-1 level remained unaffected. Our data confirm the functional involvement of Notch pathway in the pathophysiology of RA FLSs which may provide a new target for RA therapy.

Emerging roles of the γ-secretase-notch axis in inflammation

“…Inhibition of Notch signaling using γ-secretase inhibitors has been found to reduce IL-6 secretion following tumor necrosis factor (TNF) stimulation in fibroblast-like synoviocytes from rheumatoid arthritis (Jiao et al, 2012). In addition, we have recently shown that γ-secretase inhibitors and antisense-mediated down-regulation of Notch1 suppresses the severity of inflammatory arthritis and reduces the levels of active NF-κB, intracellular adhesion molecule (ICAM)-1, pro-inflammatory cytokines (TNF, IFN-γ, IL-6, IL-12, IL-17, and MCP-1), and matrix metalloprotease-3 activity in mice with collageninduced arthritis (CIA) and in RA synoviocytes (Park et al, 2013).…”

“…γ-Secretase substrate γ-Secretase cleavage product Effects in inflammatory disease References Notch NICD ALPS and SLE increase lymphoproliferation, DNT, autoantibody production, and nephritis Teachey et al, 2008 Rheumatoid arthritis mediates TNF-α-induced IL-6 production; exacerbates RA symptoms; increases ICAM-1, NF-κB, proinflammatory cytokines, Th1 and Th17 cells, Th17 cell differentiation Jiao et al, 2012Park et al, 2013Jiao et al, 2014 Multiple sclerosis induces Th1 polarization by up-regulating Tbx21; regulates Th17 differentiation; increases Th17-associated cytokine secretion; cytosol localized NICD causes remyelination failure in OPCs in MS lesion Minter et al, 2005Keerthivasan et al, 2011Nakahara et al, 2009 Sepsis mediates the production of LPS-induced cytokines Tsao et al, 2011 Asthma increases Th2 cytokine levels by up-regulating GATA-3; decreases Th1 cytokine levels Kang et al, 2009 Systemic sclerosis exacerbates dermal fibrosis; increases profibrotic cytokines Dees et al, 2011 Behcet's disease increases Th17 response Qi et al, 2014 Ulcerative colitis enhances IL-22 induced STAT3 dependent transcription Murano et al, 2014 Ischemic stroke activates microglia cells; enhances leukocytes infiltration; promotes proliferation and differentiation of reactive astrocytes Arumugam et al, 2006Wei et al, 2011Park et al, 2013Cheng et al, 2014Marumo et al, 2013Shimada et al, 2011 Allergic airway inflammation induces IL-4 production, Th2 differentiation, airway hyperresponsiveness, and eosinophilic airway inflammation Okamoto et al, 2009 Atherosclerosis increases macrophage accumulation and activity in atherosclerotic lesion; attenuates the progression of atherosclerosis Aoyama et al, 2009 Calcific aortic stenosis enhances inflammatory response to TLR4 stimulation in human aortic valve interstitial cells through regulating NF-κB activation Zeng et al, 2012 Other inflammatory responses peripheral T cell activation and proliferation (canonical & noncanonical notch signaling); induces M1 polarization of LPS-stimulated macrophage and microglial cells; inhibits eosinophil differentiation Palaga et al, 2003Dongre et al, 2014Wang et al, 2010Liu et al, 2012Kang et ...…”

“…expression of Notch target genes (Fortini, 2002). Increasing evidence suggests that Notch signaling plays an important role in the regulation of inflammatory responses in many disorders such as cardiovascular disease, rheumatoid arthritis, multiple sclerosis, asthma and stroke (Arumugam et al, 2006;Jiao et al, 2012;Kang et al, 2009;Minter et al, 2005;Quillard & Charreau, 2013).…”

Hyaluronan nanoparticles bearing γ-secretase inhibitor: In vivo therapeutic effects on rheumatoid arthritis

“…The Notch receptors are over-expressed on the inflammatory cells and synoviocytes of RA patients [7,11], and mediate the production of pro-inflammatory cytokines, immune response, and angiogenesis in RA [9,10,21]. Recently, we demonstrated that the inhibition of Notch signaling with γ-secretase inhibitor can attenuate the RA process [21].…”

“…Recent studies demonstrated that Notch receptors (Notch 1-4) and their ligands (Jagged 1-2, Delta 1,3,4), which are over-expressed in the synovial tissue of patients with RA [7,8], are responsible for inflammation and angiogenesis [9][10][11][12]. The Notch-ligand interaction leads to the translocation of the Notch intracellular domain (NICD) into the nucleus by inducing metalloprotease-and γ-secretase-mediated proteolytic cleavage [13,14].…”