TY - JOUR
T1 - Endodontic Infection–induced Inflammation Resembling Osteomyelitis of the Jaws in Toll-like Receptor 2/Interleukin 10 Double-knockout Mice
AU - Sasaki, Hajime
AU - Furusho, Hisako
AU - Rider, Daniel B.
AU - Dobeck, Justine M.
AU - Kuo, Winston Patrick
AU - Fujimura, Akira
AU - Yoganathan, Subbiah
AU - Hirai, Kimito
AU - Xu, Shuang
AU - Sasaki, Kei
AU - Stashenko, Philip
N1 - Funding Information:
Supported in part by the National Institute of Dental and Craniofacial Research /National Center for Research Resources/National Institutes of Health (grant nos. R21DE023178 , R01DE024796 , and S10RR027553 to H.S.).
Funding Information:
Supported in part by the National Institute of Dental and Craniofacial Research/National Center for Research Resources/National Institutes of Health (grant nos. R21DE023178, R01DE024796, and S10RR027553 to H.S.).
Publisher Copyright:
© 2018 American Association of Endodontists
PY - 2019/2
Y1 - 2019/2
N2 - Introduction: In general, mice develop chronic and nonhealing periapical lesions after endodontic infection. Surprisingly, we recently found that toll-like receptor 2 (TLR2)/interleukin 10 (IL-10) double-knockout (dKO) mice exhibited acute but resolving osteomyelitislike inflammation. In this study, we examined the kinetics of endodontic infection–induced inflammation in TLR2/IL-10 dKO mice and explored a potential mechanism of periapical wound healing mediated by the hypoxia-inducible factor 1 alpha (HIF-1α) subunit and arginase 1. Methods: TLR2/IL-10 dKO and wild-type C57BL/6J mice were subjected to endodontic infection in the mandibular first molars. Mice were sacrificed on days 0 (noninfected), 10, and 21 postinfection. The extent of bone destruction, inflammation, bone deposition, and gene expression were determined by micro–computed tomographic imaging, histology, bone polychrome labeling, and microarray analysis. In addition, the effect of blocking endogenous HIF-1α was tested in infected TLR2/IL-10 dKO mice using the specific inhibitor YC-1. Results: Infected TLR2/IL-10 dKO mice exhibited extensive bone destruction and inflammation on day 10 followed by spontaneous periapical wound healing including bone formation and resolution of inflammation by day 21 postinfection. In contrast, WT mice developed increasing chronic periapical inflammation over the 21-day observation period. Gene expression analyses and immunohistochemistry revealed that HIF-1α and arginase 1 were up-regulated in spontaneous wound healing in TLR2/IL-10 dKO mice. Blocking of HIF-1α in TLR2/IL-10 dKO mice using YC-1 resulted in significant inhibition of regenerative bone formation. Conclusions: The TLR2/IL-10 dKO mouse is a novel model resembling osteomyelitis of the jaws in which HIF-1α and arginase 1 appear to be crucial factors in spontaneous wound healing and bone repair.
AB - Introduction: In general, mice develop chronic and nonhealing periapical lesions after endodontic infection. Surprisingly, we recently found that toll-like receptor 2 (TLR2)/interleukin 10 (IL-10) double-knockout (dKO) mice exhibited acute but resolving osteomyelitislike inflammation. In this study, we examined the kinetics of endodontic infection–induced inflammation in TLR2/IL-10 dKO mice and explored a potential mechanism of periapical wound healing mediated by the hypoxia-inducible factor 1 alpha (HIF-1α) subunit and arginase 1. Methods: TLR2/IL-10 dKO and wild-type C57BL/6J mice were subjected to endodontic infection in the mandibular first molars. Mice were sacrificed on days 0 (noninfected), 10, and 21 postinfection. The extent of bone destruction, inflammation, bone deposition, and gene expression were determined by micro–computed tomographic imaging, histology, bone polychrome labeling, and microarray analysis. In addition, the effect of blocking endogenous HIF-1α was tested in infected TLR2/IL-10 dKO mice using the specific inhibitor YC-1. Results: Infected TLR2/IL-10 dKO mice exhibited extensive bone destruction and inflammation on day 10 followed by spontaneous periapical wound healing including bone formation and resolution of inflammation by day 21 postinfection. In contrast, WT mice developed increasing chronic periapical inflammation over the 21-day observation period. Gene expression analyses and immunohistochemistry revealed that HIF-1α and arginase 1 were up-regulated in spontaneous wound healing in TLR2/IL-10 dKO mice. Blocking of HIF-1α in TLR2/IL-10 dKO mice using YC-1 resulted in significant inhibition of regenerative bone formation. Conclusions: The TLR2/IL-10 dKO mouse is a novel model resembling osteomyelitis of the jaws in which HIF-1α and arginase 1 appear to be crucial factors in spontaneous wound healing and bone repair.
KW - Arginase 1
KW - hypoxia-inducible factor 1
KW - mouse model
KW - osteomyelitis
KW - wound healing
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U2 - 10.1016/j.joen.2018.10.007
DO - 10.1016/j.joen.2018.10.007
M3 - Article
C2 - 30711175
AN - SCOPUS:85060696931
VL - 45
SP - 181
EP - 188
JO - Journal of Endodontics
JF - Journal of Endodontics
SN - 0099-2399
IS - 2
ER -