Establishment of periodontitis treatment method by inhibition of RANK-Toll like receptor signal

MDP是负责肽聚糖免疫佐剂活性的最小基本结构单元，普遍分布在革兰氏阴性和阳性细菌的细胞壁中。MDP已被证明对免疫活性细胞具有多种生物学效应。我们已经证明，向小鼠注射MDP会导致内毒素过敏、TNF-α的产生增加和LPS攻击后致死性休克。我们还发现MDP协同增强lps诱导的人单核细胞促炎细胞因子的产生。最近，人们提出Apaf1/Nod蛋白家族成员核苷酸结合寡聚域（Nod） 2是MDP的细胞内传感器。Nod2由n端caspase募集结构域、位于中心的核苷酸结合结构域和c端富含亮氨酸的重复序列组成，并作为信号转导适配器。促炎细胞因子和LPS可增强Nod2的表达。1 α、25(OH)2D3、PGE2、LPS和…More IL-1 a刺激小鼠成骨细胞和造血细胞共培养的破骨细胞形成。在共培养中，MDP不能诱导破骨细胞的形成，但LPS、IL-1α或TNF-α对破骨细胞的形成有促进作用，而1α、25(OH)2D3和PGE2对破骨细胞的形成没有促进作用。MDP不能促进由RANKL或TNF-α诱导的破骨细胞祖细胞形成破骨细胞。在LPS或TNF-α处理的成骨细胞中，MDP上调RANKL表达，但不上调1 α，25(OH)2D3。成骨细胞对LPS、IL-1α或TNF-α表达Nod2 mRNA，但不表达1α，25(OH)2D3。LPS诱导成骨细胞Nod2 mRNA表达依赖于TLR4和MyD88。小干扰RNA对细胞内Nod2的消耗阻断了mdp诱导的成骨细胞RANKL mRNA的上调。LPS和RANKL刺激破骨细胞的存活，而MDP对这种作用没有增强作用。这些结果表明，MDP通过成骨细胞中RANKL的表达，协同促进LPS、IL-1α和TNF-a诱导的破骨细胞形成，nod2介导的信号参与了MDP诱导的成骨细胞中RANKL的表达。少

MDP, the minimal essential structural unit responsible for the immunoadjuvant activity of peptidoglycans, is distributed ubiquitously in cell walls of both Gram-negative and-positive bacteria. MDP has been shown to exert diverse biological effects on immunocompetent cells. We have shown that injection of MDP into mice resulted in endotoxin hypersensitivity : enhanced production of TNF-α and lethal shock upon challenge injection of LPS. We also showed that MDP synergistically enhanced LPS-induced proinflammatory cytokine production in human monocytic cells. Recently, it was proposed that nucleotide-binding oligomerization domain (Nod) 2, a member of the Apaf1/Nod protein family, is an intracellular sensor of MDP. Nod2 consists of an N-terminal caspase-recruitment domain, a centrally located nucleotide-binding domain and C-terminal leucine-rich repeats, and acts as a signal-transducing adaptor. Nod2 expression is enhanced by proinflammatory cytokines and LPS. 1 α,25(OH)2D3, PGE2, LPS and … More IL-1 a stimulate osteoclast formation in mouse cocultures of osteoblasts and hemopoietic cells. MDP alone could not induce osteoclast formation in the coculture, but enhanced osteoclast formation induced by LPS, IL-1α or TNF-α but not 1 α,25(OH)2D3 or PGE2. MDP failed to enhance osteoclast formation from osteoclast progenitors induced by RANKL or TNF-α. MDP up-regulated RANKL expression in osteoblasts treated with LPS or TNF-α but not 1 α,25(OH)2D3. Osteoblasts expressed mRNA of Nod2 in response to LPS, IL-1α or TNF-α but not 1 α,25(OH)2D3. Induction of Nod2 mRNA expression by LPS but not by TNF-α in osteoblasts was dependent on TLR4 and MyD88. The depletion of intracellular Nod2 by small interfering RNA blocked MDP-induced up-regulation of RANKL mRNA in osteoblasts. LPS and RANKL stimulated the survival of osteoclasts, and this effect was not enhanced by MDP. These results suggest that MDP synergistically enhances osteoclast formation induced by LPS, IL-1α and TNF-a through RANKL expression in osteoblasts, and that Nod2-mediated signals are involved in the MDP-induced RANKL expression in osteoblasts. Less