Chaves de Souza João Antônio, Frasnelli Sabrina Cruz Tfaile, Curylofo-Zotti Fabiana de Almeida, Ávila-Campos Mário Julio, Spolidório Luis Carlos, Zamboni Dario Simões, Graves Dana T, Rossa Carlos
Department of Diagnosis and Surgery, School of Dentistry at Araraquara, Universidade Estadual Paulista (UNESP), Araraquara, SP, Brazil.
Department of Microbiology, Biomedical Sciences Institute, Universidade de Sao Paulo (USP), Sao Paulo, SP, Brazil.
Immunology. 2016 Dec;149(4):374-385. doi: 10.1111/imm.12654. Epub 2016 Sep 6.
Periodontitis is a chronic inflammatory condition characterized by destruction of non-mineralized and mineralized connective tissues. It is initiated and maintained by a dysbiosis of the bacterial biofilm adjacent to teeth with increased prevalence of Gram-negative microorganisms. Nucleotide-binding oligomerization domain containing 1 (NOD1) is a member of the Nod-like receptors (NLRs) family of proteins that participate in the activation of the innate immune system, in response to invading bacteria or to bacterial antigens present in the cytoplasm. The specific activating ligand for NOD1 is a bacterial peptidoglycan derived primarily from Gram-negative bacteria. This study assessed the role of NOD1 in inflammation-mediated tissue destruction in the context of host-microbe interactions. We used mice with whole-genome deletion of the NOD1 gene in a microbe-induced periodontitis model using direct injections of heat-killed Gram-negative or Gram-negative/Gram-positive bacteria on the gingival tissues. In vitro experiments using primary bone-marrow-derived macrophages from wild-type and NOD1 knockout mice provide insight into the role of NOD1 on the macrophage response to Gram-negative and Gram-negative/Gram-positive bacteria. Microcomputed tomography analysis indicated that deletion of NOD1 significantly aggravated bone resorption induced by Gram-negative bacteria, accompanied by an increase in the numbers of osteoclasts. This effect was significantly attenuated by the association with Gram-positive bacteria. In vitro, quantitative PCR arrays indicated that stimulation of macrophages with heat-killed Gram-negative bacteria induced the same biological processes in wild-type and NOD1-deficient cells; however, expression of pro-inflammatory mediators was increased in NOD1-deficient cells. These results suggest a bone-sparing role for NOD1 in this model.
牙周炎是一种慢性炎症性疾病，其特征是非矿化和矿化结缔组织的破坏。它由邻近牙齿的细菌生物膜生态失调引发并维持，革兰氏阴性微生物的患病率增加。含核苷酸结合寡聚化结构域1（NOD1）是Nod样受体（NLRs）蛋白家族的成员，该家族蛋白参与先天免疫系统的激活，以应对入侵细菌或细胞质中存在的细菌抗原。NOD1的特异性激活配体是一种主要来源于革兰氏阴性细菌的细菌肽聚糖。本研究评估了NOD1在宿主-微生物相互作用背景下炎症介导的组织破坏中的作用。我们在微生物诱导的牙周炎模型中使用了NOD1基因全基因组缺失的小鼠，通过直接向牙龈组织注射热灭活的革兰氏阴性或革兰氏阴性/革兰氏阳性细菌。使用来自野生型和NOD1基因敲除小鼠的原代骨髓来源巨噬细胞进行的体外实验，深入了解了NOD1在巨噬细胞对革兰氏阴性和革兰氏阴性/革兰氏阳性细菌反应中的作用。微型计算机断层扫描分析表明，NOD1的缺失显著加重了革兰氏阴性细菌诱导的骨吸收，并伴有破骨细胞数量的增加。与革兰氏阳性细菌联合可显著减轻这种作用。在体外，定量PCR阵列表明，用热灭活的革兰氏阴性细菌刺激巨噬细胞在野生型和NOD1缺陷细胞中诱导相同的生物学过程；然而，促炎介质的表达在NOD1缺陷细胞中增加。这些结果表明在该模型中NOD1具有保护骨骼的作用。
