title: A p38alpha selective mitogen-activated protein kinase inhibitor prevents periodontal bone loss.
abstract: In the oral microbial environment, Gram-negative bacterial derived lipopolysaccharide (LPS) can initiate inflammatory bone loss as seen in periodontal diseases. p38 Mitogen-activated protein kinase (MAPK) signaling is critical to inflammatory cytokine and LPS-induced cytokine expression, which may contribute toward periodontal bone loss. The purpose of this proof-of-principle study was to evaluate the ability of an orally active p38alpha MAPK inhibitor (SD-282) to reduce periopathogenic LPS-induced alveolar bone loss in an experimental rat model. Five groups of Sprague-Dawley rats received one of the following treatments: LPS injected to the palatal gingiva adjacent to the maxillary molars three times per week for 8 weeks, LPS plus two doses of SD-282 (15 or 45 mg/kg) twice daily by oral gavage, or control groups given drug vehicle (1% polyethylene glycol) or SD-282 (45 mg/kg) only. Baseline and 8-week alveolar bone loss was assessed by microcomputed tomography (microCT) and histological examination. LPS induced severe bone loss over this time period, whereas control groups were unchanged from baseline measurements. Both doses of SD-282 showed significant protection from LPS-induced bone loss. Bone area and volumetric analysis of maxillas by microCT indicated significant loss of bone volume with LPS treatment, which was blocked with the p38 inhibitor. Histological examination indicated significantly fewer tartate-resistant acid phosphatase-positive osteoclasts and a significant decrease in interleukin (IL)-6, IL-1beta, and tumor necrosis factor alpha expression in p38 inhibitor-treated groups compared with LPS groups by immunostaining. Results from this in vivo study suggest that orally active p38 MAPK inhibitors can reduce LPS-induced inflammatory cytokine production and osteoclast formation and protect against LPS-stimulated alveolar bone loss.
authors.affiliation: Department of Periodontics and Oral Medicine, University of Michigan, 1011 N. University Ave., Ann Arbor, MI 48109-1078, USA. klkirk@umich.edu
authors.forename: Keith L
authors.initials: KL
authors.lastname: Kirkwood
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.forename: Jill E
authors.initials: JE
authors.lastname: Rogers
authors.forename: Jodie
authors.initials: J
authors.lastname: Otremba
authors.forename: Derek D
authors.initials: DD
authors.lastname: Coatney
authors.forename: Jaclynn M
authors.initials: JM
authors.lastname: Kreider
authors.forename: Nisha J
authors.initials: NJ
authors.lastname: D'Silva
authors.forename: Sarvajit
authors.initials: S
authors.lastname: Chakravarty
authors.forename: Sundeep
authors.initials: S
authors.lastname: Dugar
authors.forename: Linda S
authors.initials: LS
authors.lastname: Higgins
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Protter
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Medicherla
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology / Q000517:prevention & control*; D000818:Animals; D016207:Cytokines / Q000096:biosynthesis; D005260:Female; D007211:Indoles / Q000627:therapeutic use*; D008070:Lipopolysaccharides / Q000633:toxicity; D010010:Osteoclasts / Q000187:drug effects / Q000502:physiology; D010518:Periodontitis / Q000188:drug therapy; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D053245:RANK Ligand / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology
chemical_list: D016207:Cytokines; D007211:Indoles; D008070:Lipopolysaccharides; D047428:Protein Kinase Inhibitors; D053245:RANK Ligand; C514526:indole-5-carboxamide; D048051:p38 Mitogen-Activated Protein Kinases