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.

Zhu L ，Wu Y ，Wei H ，Yang S ，Zhan N ，Xing X ，Peng B ... -  《-》

IL-17R activation of human periodontal ligament fibroblasts induces IL-23 p19 production: Differential involvement of NF-κB versus JNK/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. This study hypothesised that Th17 signature cytokine IL-17 may target specialised human periodontal ligament fibroblasts (hPDLFs) for production of IL-23 p19, a key subunit of IL-23. Primary hPDLFs had steady expression of IL-17 receptor (IL-17R) mRNA and surface-bound protein. IL-17 was capable of stimulating the expression of IL-23 p19 mRNA and protein in cultured hPDLFs, which was attenuated by IL-17 or IL-17R neutralising antibodies. In accordance with the enhanced expression of IL-23 p19, IL-17 stimulation resulted in rapid activation of Akt, p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK) 1/2, c-Jun-N-terminal kinase (JNK), nuclear factor-kappaB (NF-κB), and activator protein-1 (AP-1) in hPDLFs. Inhibitors of Akt, p38 MAPK, ERK 1/2, or NF-κB significantly suppressed, whereas blocking JNK and AP-1 substantially augmented IL-23 p19 production from IL-17-stimulated hPDLFs. Moreover, IL-17-initiated NF-κB activation was blocked by Akt, p38 MAPK, or ERK 1/2 inhibition, while AP-1 activity was specifically abrogated by JNK inhibition. Thus, these results provide evidence that hPDLFs are a target of Th17, and that IL-17 appears to up-regulate the expression of IL-23 p19 via a homeostatic mechanism involving Akt-, p38 MAPK-, and ERK 1/2-dependent NF-κB signalling versus the JNK/AP-1 pathway. Taken together, our findings suggest that disruption of the interaction between IL-17 and IL-23 may be a potential therapeutic approach in the treatment of periodontitis.

Zhu L ，Wu Y ，Wei H ，Xing X ，Zhan N ，Xiong H ，Peng B ... -  《-》

MAPKs, activator protein-1 and nuclear factor-κB mediate production of interleukin-1β-stimulated cytokines, prostaglandin E₂ and MMP-1 in human periodontal ligament cells.

Determination of the interleukin-1 (IL-1) signaling cascades that lead to the production of various inflammatory mediators and catabolic factors may clarify attractive targets for therapeutic intervention for periodontitis. We comprehensively assessed the involvement of MAPKs, activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) in IL-1β-induced production of interleukin-6 (IL-6), interleukin-8 (IL-8), prostaglandin E(2) (PGE(2) ) and MMP-1 in human periodontal ligament cells. Human periodontal ligament cells were pretreated with an inhibitor for each of the MAPKs or NF-κB and subsequently treated with IL-1β. Following treatment, phosphorylation of three types of MAPK (ERK, p38 MAPK and c-Jun N-terminal kinase), IκB kinase (IKK) α/β/γ and IκB-α, as well as the DNA binding activity of AP-1 and NF-κB and the production of IL-6, IL-8, PGE(2) and MMP-1, were determined by western blotting, a gel mobility shift assay and ELISA, respectively. The three MAPKs, simultaneously activated by IL-1β, mediated the subsequent DNA binding of AP-1 at various magnitudes, while IKKα/β/γ, IκB-α and NF-κB were also involved in the IL-1 signaling cascade. Furthermore, IL-1β stimulated the production of IL-6, IL-8, PGE(2) and MMP-1 via activation of the three MAPKs and NF-κB, because inhibitors of these significantly suppressed the IL-1β-stimulated production of these factors. Our results strongly suggest that MAPK, AP-1 and NF-κB mediate the IL-1β-stimulated synthesis of IL-6, IL-8, PGE(2) and MMP-1 in human periodontal ligament cells. Therefore, inhibition of activation of MAPK, AP-1 and/or NF-κB may lead to therapeutic effects on progression of periodontitis.

Murayama R ，Kobayashi M ，Takeshita A ，Yasui T ，Yamamoto M ... -  《-》

Interleukin-1beta induces ICAM-1 expression enhancing leukocyte adhesion in human rheumatoid arthritis synovial fibroblasts: involvement of ERK, JNK, AP-1, and NF-kappaB.

Yang CM ，Luo SF ，Hsieh HL ，Chi PL ，Lin CC ，Wu CC ，Hsiao LD ... -  《-》

Endothelin-1 stimulates proinflammatory cytokine expression in human periodontal ligament cells via mitogen-activated protein kinase pathway.

Liang L ，Yu J ，Zhou W ，Liu N ，E LL ，Wang DS ，Liu H ... -  《-》