Table 1.
Characteristics of the patients.
Fig 1.
Study design of the murine model of experimental periodontitis.
Fig 2.
Characterization of human gingival samples in healthy and patients affected by chronic periodontitis.
A. Samples were stained for the T lymphocytes marker CD3 (arrows). Sections were counterstained with Harris Hematoxylin staining. EP: Epithelium; CT: Connective Tissue. B. TNF-α and IL-6 expression in healthy and CP patients were measured by RT-qPCR. Data are shown as mean ± SD. Healthy samples n = 9; chronic periodontitis samples n = 13. Bar = 250μm. *p<0.05, **p<0.01.
Fig 3.
IL-33 and RANK-L expressions in gingival samples of healthy and patients affected by chronic periodontitis.
A. mRNA encoding for IL-33 was quantified by RT-qPCR. B. Healthy and CP gingival samples were immunostained for IL-33 (arrows). The percentage of cells positive for IL-33 was quantified using Fiji software and defined as a percentage of DAB positive staining area per region of interest. C. mRNA encoding for RANK-L was quantified by RT-qPCR. D. Healthy and CP gingival samples were immunostained for RANK-L (arrows). The percentage of cells positive for RANK-L was quantified using Fiji software and defined as a percentage of DAB positive staining area per region of interest. EP: Epithelium; CT: Connective Tissue. Data are shown as mean ± SEM. Healthy samples n = 9; Chronic periodontitis samples (CP) n = 13. Bar = 250μm. *p<0.05; **p<0.01; ***p<0.001.
Fig 4.
Time-course of alveolar bone loss in the ligature-induced murine model of experimental periodontitis.
CD1 Swiss mice (n = 90) were subjected to experimental periodontitis for 4, 14 and 28 days. At each time point, animals were sacrificed and maxillary samples were harvested. A. After 4, 14 and 28 days, μCT analysis was performed. Longitudinal sections through the middle of the palatal root of the first maxillary molar (left images) and transversal sections from the apices of the three roots of the first maxillary molar to the summit of the alveolar bone crest (right images) are presented for each time points. B. Alveolar bone loss was assessed using 2D μCT. At each time point, data of ligatured groups (Lig and Pg L) were compared to their respective Sham groups. Data are shown as means ± SEM. * p<0.05.
Fig 5.
Time-course of IL-33 expression in the ligature-induced murine model of experimental periodontitis.
A. IL-33 expression was assessed by IHC and sections were counterstained with Harris Hematoxylin staining (arrows). B. The percentage of IL-33 was quantified in gingival epithelium and in connective tissue using Fiji software and defined as a percentage of DAB positive staining area per region of interest. At each time point, data of ligatured groups (Lig and Pg L) were compared to their respective Sham groups. EP: Epithelium, CT: Connective tissue. Data are shown as means ± SEM. * p<0.05; **p<0.01. Scale bar = 100μm.
Fig 6.
IL-33 induced RANK-L expression in mouse gingival explants.
Explants from palatal mucosa of C57BL/6 mice were culture overnight at 37°C. These explants were then stimulated with 100ng/mL of recombinant murine IL-33 for 24 hours. Total tissue RNA was extracted and RANK-L transcript was quantified by RT-qPCR. Three separate experiments were performed. Data are shown are means ± SEM. *p<0.05.
Fig 7.
Pg infection increased the expression of RANK-L and IL-33 mRNAs in human oral epithelial cells.
Human oral epithelial cells (OKF6/TERT2) were cultured with Pg at 10:1 or 100:1 MOI for 6, 12 or 24 hours. mRNAs encoding for IL-33 (A) and RANK-L ((B) were quantified by RT-qPCR. Three separate sets of experiment were performed. Data are shown as mean ± SEM. *p<0.05; **p<0.01.