Oncostatin M-induced matrix metalloproteinase and tissue inhibitor of metalloproteinase-3 genes expression in chondrocytes requires Janus kinase/STAT signaling pathway

Oncostatin M (OSM), a member of the IL-6 superfamily of cytokines, is elevated in patients with rheumatoid arthritis and, in synergy with IL-1, promotes cartilage degeneration by matrix metalloproteinases (MMPs). We have previously shown that OSM induces MMP and tissue inhibitor of metalloproteinase-3 (TIMP-3) gene expression in chondrocytes by protein tyrosine kinase-dependent mechanisms. In the present study, we investigated signaling pathways regulating the induction of MMP and TIMP-3 genes by OSM. We demonstrate that OSM rapidly stimulated phosphorylation of Janus kinase (JAK) 1, JAK2, JAK3, and STAT1 as well as extracellular signal-regulated kinase (ERK) 1/2, p38, and c-Jun N-terminal kinase 1/2 mitogen-activated protein kinases in primary bovine and human chondrocytes. A JAK3-specific inhibitor blocked OSM-stimulated STAT1 tyrosine phosphorylation, DNA-binding activity of STAT1 as well as collagenase-1 (MMP-1), stromelysin-1 (MMP-3), collagenase-3 (MMP-13), and TIMP-3 RNA expression. In contrast, a JAK2-specific inhibitor, AG490, had no impact on these events. OSM-induced ERK1/2 activation was also not affected by these inhibitors. Similarly, curcumin (diferuloylmethane), an anti-inflammatory agent, suppressed OSM-stimulated STAT1 phosphorylation, DNA-binding activity of STAT1, and c-Jun N-terminal kinase activation without affecting JAK1, JAK2, JAK3, ERK1/2, and p38 phosphorylation. Curcumin also inhibited OSM-induced MMP-1, MMP-3, MMP-13, and TIMP-3 gene expression. Thus, OSM induces MMP and TIMP-3 genes in chondrocytes by activating JAK/STAT and mitogen-activated protein kinase signaling cascades, and interference with these pathways may be a useful approach to block the catabolic actions of OSM.     

Interleukin-1 stimulates cytokines, prostaglandin E2 and matrix metalloproteinase-1 production via activation of MAPK/AP-1 and NF-kappaB in human gingival fibroblasts

Interleukin-1 (IL-1) plays a crucial role in the immunopathological responses involved with tissue destruction in chronic inflammatory diseases, such as periodontal disease, as it stimulates host cells including fibroblasts to produce various inflammatory mediators and catabolic factors. We comprehensively investigated the involvement of mitogen-activated protein kinases (MAPKs)/activator protein-1 (AP-1) and IkappaB kinases (IKKs)/IkappaBs/nuclear factor-kappaB (NF-kappaB) in IL-1beta-stimulated IL-6, IL-8, prostaglandin E(2) (PGE(2)) and matrix metalloproteinase-1 (MMP-1) production by human gingival fibroblasts (HGF). Three MAPKs, extracellular signal-regulated kinase (ERK), p38 MAPK and c-Jun N-terminal kinase (JNK), which were simultaneously activated by IL-1beta, mediated subsequent c-fos and c-jun mRNA expression and DNA binding of AP-1 at different magnitudes. IKKalpha/beta/IkappaB-alpha/NF-kappaB was also involved in the IL-1 signaling cascade. Further, IL-1beta stimulated HGF to produce IL-6, IL-8, PGE(2) and MMP-1 via activation of the 3 MAPKs and NF-kappaB, as inhibitors of each MAPK and NF-kappaB significantly suppressed the production of IL-1beta-stimulated factors, though these pathways might also play distinct roles in IL-1beta activities. Our results strongly suggest that the MAPKs/AP-1 and IKK/IkappaB/NF-kappaB cascades cooperatively mediate the IL-1beta-stimulated synthesis of IL-6, IL-8, PGE(2) and MMP-1 in HGF.     

Involvement of integrins, MAPK, and NF-kappaB in regulation of the shear stress-induced MMP-9 expression in endothelial cells

Variations in the matrix metalloproteinase (MMP)-9 gene are related to the presence and severity of atherosclerosis. The aim of this study was to determine the signaling pathways of MMP-9 in endothelial cells subjected to low fluid shear stress. We found that low fluid shear stress significantly increased MMP-9 expression, IkappaBalpha degradation, NF-kappaB DNA-binding activity and phosphorylation of MAPK in cultured human umbilical vein endothelial cells (HUVECs). Inhibition of NF-kappaB resulted in remarkable downregulation of stress-induced MMP-9 expression. Pretreatment of HUVECs with inhibitors of p38 mitogen-activating protein kinase (MAPK) and extracellular signal-regulated kinase1/2 (ERK1/2) also led to significant suppression of stress-induced MMP-9 expression and NF-kappaB DNA-binding activity. Similarly, addition of integrins inhibitor to HUVECs suppressed the stress-induced MMP-9 expression, IkappaBalpha degradation, NF-kappaB DNA-binding activity and the phosphorylation of p38 MAPK, ERK1/2. Our findings demonstrated that the shear stress-induced MMP-9 expression involved integrins-p38 MAPK or ERK1/2-NF-kappaB signaling pathways.     

Differential activation of mitogen-activated protein kinases in AGS gastric epithelial cells by cag+ and cag- Helicobacter pylori.

The aim of this study was to determine whether Helicobacter pylori activates mitogen-activated protein (MAP) kinases in gastric epithelial cells. Infection of AGS cells with an H. pylori cag+ strain rapidly (5 min) induced a dose-dependent activation of extracellular signal-regulated kinases (ERK), p38, and c-Jun N-terminal kinase (JNK) MAP kinases, as determined by Western blot analysis and in vitro kinase assay. Compared with cag+ strains, cag- clinical isolates were less potent in inducing MAP kinase, particularly JNK and p38, activation. Isogenic inactivation of the picB region of the cag pathogenicity island resulted in a similar loss of JNK and p38 MAP kinase activation. The specific MAP kinase inhibitors, PD98059 (25 microM; MAP kinase kinase (MEK-1) inhibitor) and SB203580 (10 microM; p38 inhibitor), reduced H. pylori-induced IL-8 production in AGS cells by 78 and 82%, respectively (p < 0.01 for each). Both inhibitors together completely blocked IL-8 production (p < 0.001). However, the MAP kinase inhibitors did not prevent H. pylori-induced IkappaBalpha degradation or NF-kappaB activation. Thus, H. pylori rapidly activates ERK, p38, and JNK MAP kinases in gastric epithelial cells; cag+ isolates are more potent than cag- strains in inducing MAP kinase phosphorylation and gene products of the cag pathogenicity island are required for maximal MAP kinase activation. p38 and MEK-1 activity are required for H. pylori-induced IL-8 production, but do not appear to be essential for H. pylori-induced NF-kappaB activation. Since MAP kinases regulate cell proliferation, differentiation, programmed death, stress, and inflammatory responses, activation of gastric epithelial cell MAP kinases by H. pylori cag+ strains may be instrumental in inducing gastroduodenal inflammation, ulceration, and neoplasia.     

Multiple signaling conduits regulate global differentiation-specific gene expression in PC12 cells

PC12 cells serve as a model for exploring nerve growth factor (NGF)-stimulated signal pathways that mediate neural differentiation. We previously demonstrated that neurofilament light chain (NFLC) gene induction by NGF requires collaborative extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling. Herein, we investigate the broader requirement for integrated ERK and JNK signaling in NGF-stimulated gene expression. NGF stimulates differentiation as well as maintenance of cell viability while insulin-like growth factor-1 (IGF-1) stimulates only trophic actions in PC12 cells. Affymetrix Genechips were used to identify genes whose expression specifically increased in response to NGF, but not IGF-1. From the set of NGF-specific genes, the induction by NGF of ten genes with diverse predicted cellular functions was tested for ERK and JNK pathway requirements using the protein kinase inhibitors, PD98059 and SP600125, respectively. Like NFLC, induction of urokinase plasminogen activator (uPAR), transin/matrix metalloproteinase 3 (MMP3), Fra-1 and transforming growth factor beta 1 (TGF beta 1) required collaborative ERK and JNK signaling while the increased expression of cortexin, rat collapsin response mediator protein 4 (rCRMP4), rat growth and transformation-dependent protein (RGT), and synapsin II required neither mitogen-activated protein kinase (MAPK) pathway. NGF-induction of the bradykinin B2 receptor and c-Ret mRNAs was partially inhibited by SP600125, but not PD98059. Reporter constructs containing the promoters for ERK/JNK-dependent genes (NFLC, transin, uPAR) as well as an ERK/JNK-independent gene (synapsin II) revealed that both sets of genes required functional Ras signaling for activation by NGF. Integrated signaling through the ERK and JNK MAPKs, therefore, represents a general conduit for NGF-dependent gene expression, but additional Ras-dependent signaling pathways distinct from the ERKs and JNKs must contribute as well. Thus, multiple signaling conduits control global differentiation-specific gene expression in PC12 cells.     

Carbon monoxide inhibits IL-17-induced IL-6 production through the MAPK pathway in human pulmonary epithelial cells

Interleukin (IL)-17 is a proinflammatory cytokine that is produced by activated memory CD4 T cells, which regulates pulmonary neutrophil emigration by the induction of CXC chemokines and cytokines. IL-17 constitutes a potential target for pharmacotherapy against exaggerated neutrophil recruitment in airway diseases. As a cytoprotective and anti-inflammatory gaseous molecule, carbon monoxide (CO) may also regulate IL-17-induced inflammatory responses in pulmonary cells. Herein, we examine the production of cytokine IL-6 induced by IL-17 and the effect of CO on IL-17-induced IL-6 production in human pulmonary epithelial cell A549. We first show that IL-17 can induce A549 cells to release IL-6 and that CO can markedly inhibit IL-17-induced IL-6 production. IL-17 activated the ERK1/2 MAPK pathway but did not affect p38 and JNK MAPK pathways. CO exposure selectively attenuated IL-17-induced ERK1/ERK2 MAPK activation without significantly affecting either JNK or p38 MAPK activation. Furthermore, in the presence of U0126 and PD-98059, selective inhibitors of MEK1/2, IL-17-induced IL-6 production was significantly attenuated. We conclude that CO inhibits IL-17-stimulated inflammatory response via the ERK1/2-dependent pathway.     

Interleukin-4 antagonizes oncostatin M and transforming growth factor beta-induced responses in articular chondrocytes

Oncostatin M (OSM) stimulates cartilage degradation in rheumatoid arthritis (RA) by inducing matrix metalloproteinases (MMPs) and aggrecanases (ADAMTS; a disintegrin and metalloproteinase with thrombospondin motif). Transforming growth factor beta (TGF-beta1) induces cartilage repair in joints but in excessive amounts, promotes inflammation. OSM and TGF-beta1 also induce tissue inhibitor of metalloproteinase-3 (TIMP-3), an important natural inhibitor of MMPs, aggrecanases, and tumor necrosis factor alpha converting enzyme (TACE), the principal proteases involved in arthritic inflammation and cartilage degradation. We studied cartilage protective mechanisms of the antiinflammatory cytokine, interleukin-4 (IL-4). IL-4 strongly (MMP-13 and TIMP-3) or minimally (ADAMTS-4) suppressed OSM-induced gene expression in chondrocytes. IL-4 did not affect OSM-stimulated phosphorylation of extracellular signal-regulated kinases (ERKs), protein 38 (p38), c-Jun N-terminal kinase (JNK) and Stat1. Lack of additional suppression with their inhibitors suggested that MMP-13, ADAMTS-4, and TIMP-3 inhibition was independent of these mediators. IL-4 also downregulated TGF-beta1-induced TIMP-3 gene expression, Smad2, and JNK phosphorylation. Additional suppression of TIMP-3 RNA by JNK inhibitor suggests JNK implication. The cartilage protective effects of IL-4 in animal models of arthritis may be due to its inhibition of MMPs and ADAMTS-4 expression. However, suppression of TIMP-3 suggests caution for using IL-4 as a cartilage protective therapy.     

Up-regulation of IL-23 p19 expression in human periodontal ligament fibroblasts by IL-1β via concurrent activation of the NF-κB and MAPKs/AP-1 pathways

Interleukin (IL)-23 is an essential cytokine involved in the expansion of a novel CD4(+) T helper subset known as Th17, which has been implicated in the pathogenesis of periodontitis recently. Our previous study first identified specialized human periodontal ligament fibroblasts (hPDLFs) as an important production source of IL-23. The present study was undertaken to investigate the effects of the pro-inflammatory and Th17-polarizing mediator IL-1β on hPDLFs-mediated IL-23 p19 production, and the molecular mechanism involved. IL-23 p19 expression was in situ detected in IL-1β-stimulated hPDLFs. IL-1β was capable of stimulating the expression of IL-23 p19 mRNA and protein in cultured hPDLFs, which was attenuated by IL-1 receptor antagonist (IL-1Ra) or myeloid differentiation primary response gene 88 (MyD88) inhibitor. Meanwhile, inhibitors of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK) 1/2, c-Jun-N-terminal kinase (JNK), activator protein-1 (AP-1), or nuclear factor-kappaB (NF-κB) significantly suppressed IL-23 p19 production from IL-1β-stimulated hPDLFs. Moreover, IL-1β-initiated AP-1 activation was blocked by p38 MAPK, ERK 1/2, or JNK inhibition, whereas NF-κB activity remained unaltered by all the above pathway specific inhibitors. Thus, these results provide evidence that Th17-polarizing mediator IL-1β up-regulated the expression of IL-23 p19 in hPDLFs via NF-κB signaling and MAPKs-dependent AP-1 pathways. Taken together, our findings indicate that IL-1Ra may be used therapeutically to inhibit Th17-driven inflammatory diseases including periodontitis.