Negative Regulation of Innate Immune Responses through MAPK Phosphatases

描述（由申请人提供）：牙周病的发生和进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。p38 MARK中由周围病变LPS激活的主要信号通路之一。在p38磷酸化之后，p38 MAP激酶的失活主要是由双特异性MAP激酶磷酸酶（MKP）家族实现的。MKP-1能够负调控p38 MAP激酶的转录和转录后活性。MKP-1有助于脂多糖耐受性，并且MKP-1的过度表达已被证明会加速p38失活，导致促炎细胞因子的产生减少。我们最近发现lps诱导的IL-6 mRNA稳定表达需要p38信号。本研究的初步数据表明，在MKP- 1转染的细胞中，lps诱导的IL-6表达明显减弱。此外，我们提供的重要数据显示p38是lps诱导牙周骨破坏的主要信号通路。基于这些数据，我们假设p38信号的内源性负调节机制MKP-1是负责衰减lps诱导的巨噬细胞炎症细胞因子表达的关键成分。在本研究中，TIP过表达减少炎症的能力将通过巨噬细胞基因靶向策略和实验性牙周炎模型在体外确定。具体目的是：1)确定过表达MKP-1在体外对IL-6和TNFa mRNA表达的影响。2)研究MKP-1在原代骨髓巨噬细胞炎症细胞因子生成和lps诱导的破骨细胞生成中的作用；3)研究MKP-1在MKP小鼠体内炎症性骨破坏中的作用。这些研究将通过选择性衰减p38 mapk诱导的牙周骨破坏信号，确定lps诱导的细胞因子表达和负调控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.