Molecular imaging assessment of periodontitis lesions in an
experimental mouse model
Received: 12 October 2017 / Accepted: 31 May 2018
Springer-Verlag GmbH Germany, part of Springer Nature 2018
Objective We aimed to evaluate molecular imaging as a novel diagnostic tool for mice periodontitis model induced by ligature
and Porphyromonas gingivalis (Pg) inoculation.
Materials and methods Twelve female mice were assigned to the following groups: no treatment as control group (n =4);
periodontitis group induced by ligature and Pg as Pg group (n = 4); and Pg group treated with glycyrrhizinic acid (GA) as Pg
+GAgroup(n = 4). All mice were administered a myeloperoxidase (MPO) activity-specific luminescent probe and observed
using a charge-coupled device camera on day 14. Image analysis on all mice was conducted using software to determine the
signal intensity of inflammation. Additionally, histological and radiographic evaluation for periodontal inflammation and bone
resorption at the site of periodontitis, and quantitative enzyme-linked immunosorbent assay (ELISA) were conducted on three
mice for each group. Each experiment was performed three times.
Results Levels of serum IgG antibody against P. gingivalis were significantly higher in the Pg than in the Pg + GA group.
Histological analyses indicated that the number of osteoclasts and neutrophils were significantly lower in the Pg + GA than in the
Pg group. Micro-CT image analysis indicated no difference in bone resorption between the Pg and Pg + GA groups. The signal
intensity of MPO activity was detected on the complete craniofacial image; moreover, strong signal intensity was localized
specifically at the periodontitis site in the ex vivo palate, with group-wise differences.
Conclusions Molecular imaging analysis based on MPO activity showed high sensitivity of detection of periodontal inflamma-
tion in mice.
Clinical relevance Molecular imaging analysis based on MPO activity has potential as a diagnostic tool for periodontitis.
Periodontitis is a chronic inflammatory disease caused by an
immunoreaction to periodontal pathogens in the subgingival
biofilm and is one of the most prevalent infectious diseases
worldwide . Porphyromonas gingivalis has been described
as one of the most virulent bacteria involved in the onset and
exacerbation of periodontitis, and the representative pathogens
are known to influence oral infection and systemic host re-
sponses . Recently, the relationship between oral infectious
diseases and other systemic diseases has been revealed .
Dentists usually perform periodontal examinations, such as
measuring the pocket-probing depth and plain radiography,
for periodontal assessment ; in addition, some clinical indi-
ces, such as periodontal inflamed surface area (PISA), are used
clinically . However, these examinations do not accurately
reflect the spatiotemporal changes in periodontal inflammation
and are not common tests, such as blood tests, bacterial tests,
urinalysis, or computed tomography (CT) that can generally
be performed by medical staff. Collaboration between re-
searchers in medicine and dentistry is required to develop in-
terdisciplinary examinations. Although some candidate exam-
inations, such as bacterial tests using saliva samples andthe
serum immunoglobulin G (IgG) test against periodontal
* Shogo Takashiba
Department of Pathophysiology - Periodontal Science, Okayama
University Graduate School of Medicine, Dentistry and
Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku,
Okayama 700-8525, Japan
Clinical Oral Investigations