Role of NOD2 and RIP2 in host-microbe interactions with Gram-negative bacteria: insights from the periodontal disease model.
NOD2 is a member of the NLR family of proteins that participate in the activation of the innate immune response. RIP2 is a downstream kinase activated by both NOD1 and NOD2. There is scarcity of information regarding the relevance of NOD2 in periodontitis, a chronic inflammatory condition characterized by inflammatory bone resorption. We used NOD2-KO and RIP2-KO mice in a model of microbial-induced periodontitis. Heat-killed Aggregatibacter actinomycetemcomitans was injected in the gingival tissues three times/wk for 4 wk. Bone resorption was assessed by μCT analysis; osteoclasts were identified by immunohistochemical staining for TRAP and inflammation was assessed using a severity score system in H/E-stained sections. In vitro studies using primary macrophages assessed the response macrophages using qPCR-based array and multi-ligand ELISA. Bone resorption and osteoclastogenesis were significantly reduced in NOD2-KO mice. Severity of inflammation was not affected. qPCR-focused arrays and multi-ligand ELISA showed that expression of pro-inflammatory mediators was reduced in NOD2- and RIP2-deficient cells. RANKL-induced osteoclastogenesis was impaired in NOD2- and RIP2-deficient macrophages. We conclude that NOD2 is important for osteoclast differentiation and inflammatory bone resorption in vivo and also for the macrophage response to Gram-negative bacteria.
1 Department of Diagnosis and Surgery, School of Dentistry at Araraquara-Univ Estadual Paulista (UNESP), Araraquara, SP, Brazil.
Joao Ac
JA
Souza
1 Department of Diagnosis and Surgery, School of Dentistry at Araraquara-Univ Estadual Paulista (UNESP), Araraquara, SP, Brazil.
Marcell C
MC
Medeiros
1 Department of Diagnosis and Surgery, School of Dentistry at Araraquara-Univ Estadual Paulista (UNESP), Araraquara, SP, Brazil.
Fernanda Rg
FR
Rocha
1 Department of Diagnosis and Surgery, School of Dentistry at Araraquara-Univ Estadual Paulista (UNESP), Araraquara, SP, Brazil.
Sabrina G
SG
de Aquino
2 Department of Microbiology, Institute of Biomedical Sciences-Univ de Sao Paulo (USP), Sao Paulo, SP, Brazil.
Mario J
MJ
Ávila-Campos
3 Department of Physiology and Pathology, School of Dentistry at Araraquara-Univ Estadual Paulista (UNESP), Araraquara, SP, Brazil.
Luis C
LC
Spolidorio
4 Department of Cell, Molecular Biology and Biopathogenic Agents, School of Medicine at Ribeirao Preto-Univ de Sao Paulo (USP), Ribeirao Preto, SP, Brazil.
Dario S
DS
Zamboni
5 Department of Periodontics, School of Dental Medicine-University of Pennsylvania, Philadelphia, PA, USA.
Dana T
DT
Graves
1 Department of Diagnosis and Surgery, School of Dentistry at Araraquara-Univ Estadual Paulista (UNESP), Araraquara, SP, Brazil.
Carlos
C
Rossa
D000818:Animals; D001862:Bone Resorption / Q000276:immunology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D016905:Gram-Negative Bacterial Infections / Q000276:immunology*; D018836:Inflammation Mediators / Q000378:metabolism; D008264:Macrophages / Q000382:microbiology / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053473:Nod2 Signaling Adaptor Protein / Q000235:genetics / Q000378:metabolism*; D010012:Osteogenesis / Q000276:immunology*; D010518:Periodontitis / Q000276:immunology*; D053245:RANK Ligand / Q000378:metabolism; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
D018836:Inflammation Mediators; D053473:Nod2 Signaling Adaptor Protein; C495945:Nod2 protein, mouse; D053245:RANK Ligand; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C506255:Ripk2 protein, mouse
Bone resorption; NOD2 signaling adaptor protein; inflammation; innate immunity; macrophages