Negative Regulation of Innate Immune Responses through MAPK Phosphatases

描述(由申请人提供)：牙周病的发生和发展是宿主对口腔病原体的免疫炎症反应的结果。炎症细胞因子的产生是一个高度调控的过程，涉及转录和转录后机制。P38Mark中致病内毒素激活的主要信号转导通路之一。P38磷酸化后，p38 MAP的失活主要是通过一系列双特异性MAP磷酸酶(MKP)来实现的。MKP-1对转录和转录后p38 MAPK活性均有负性调节作用。MKP-1参与内毒素耐受，过度表达MKP-1可加速p38失活，导致促炎细胞因子产生减少。我们最近发现，内毒素诱导的IL-6mRNA的稳定表达需要p38信号。初步数据表明，在MKP-1转基因细胞中，内毒素诱导的IL-6表达显著减弱。此外，我们还提供了有意义的数据，表明p38是导致脂多糖诱导的牙周骨破坏的主要信号通路。基于这些数据，我们推测p38信号的内源性负调控机制MKP-1是内毒素诱导巨噬细胞炎性细胞因子表达减弱的关键成分。在这项建议中，TIP过度表达减轻炎症的能力将在体外使用巨噬细胞中的基因靶向策略来确定，并在体内使用实验性牙周炎模型来确定。目的：1)体外研究MKP-1过表达对IL-6和TNFa基因表达的影响。2)确定MKP-1在原代骨髓巨噬细胞炎性细胞因子产生和内毒素诱导的破骨细胞形成中的作用；3)利用MKP小鼠，研究MKP-1在体内炎症性骨破坏中的作用。这些研究将通过选择性地减弱p38MAPK诱导的信号在牙周骨破坏中的作用，确定内毒素诱导的细胞因子表达和负性调节在炎症性骨丢失中的作用。

DESCRIPTION (provided by applicant): Periodontal disease initiation and progression occurs as a consequence of the host immune inflammatory response to oral pathogens. The production of inflammatory cytokines is a highly regulated process involving transcriptional and posttranscriptional mechanisms. One of the major signaling pathways activated by periopathogenic LPS in p38 MARK. Following p38 phosphorylation, inactivation of p38 MAP kinases is achieved mainly by a family of dual-specific MAP kinase phosphatases (MKP). MKP-1 is capable of negatively regulating both transcriptional and post transcriptional p38 MAP kinase activity. MKP-1 contributes towards LPS tolerance and over-expression of MKP-1 has shown to accelerate p38 inactivation resulting in diminished proinflammatory cytokine production. We have recently shown that LPS-induced IL-6 mRNA stability expression requires p38 signaling. Preliminary data for this proposal indicates that in MKP- 1 transfected cells, LPS-induced IL-6 expression is significantly attenuated. In addition, we have provided significant data showing the p38 is a major signaling pathway contributing to LPS-induced periodontal bone destruction. Based upon these data, we hypothesize that the endogenous negative regulator mechanism of p38 signaling, MKP-1, is a key component of responsible for attenuation of LPS-induced inflammatory cytokine expression in macrophages. In this proposal, the ability of TIP over-expression to decrease inflammation will be determined in vitro using gene targeted strategies in macrophages, and in vivo using experimental periodontitis models. The specific aims are 1) To determine the role of over-expressed MKP-1 on IL-6 and TNFa mRNA expression in vitro. 2) To determine the contribution of MKP-1 in ontogeny of inflammatory cytokine production and LPS-induced osteoclastogenesis in primary bone marrow macrophages and 3) To determine the impact of MKP-1 in inflammatory bone destruction in vivo using MKP mice. These studies will establish the role of LPS-induced cytokine expression and negative regulation in inflammatory bone loss through selective attenuation of p38 MAPK-induced signaling in periodontal bone destruction.