A pilot study on the expression of circadian clock genes in the alveolar bone of mice with periodontitis

ABSTRACT

This study aimed to investigate the expression of circadian clock genes in mouse alveolar bone, and the possible reasons for these changes. Fifty C57 mice were orally inoculated with P. gingivalis, establishing a model of periodontitis using healthy mice as controls. The alveolar bone of both groups was taken for micro-computed tomography scanning to measure the amount of attachment loss, and the relative expression of mRNA in each clock gene and periodontitis related inflammatory factor was detected by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR). After the establishment of the mouse model, the height of alveolar bone in the periodontitis group was significantly lower than that in the normal group (p < 0.05). The relative transcriptional level of Bmal1, Per2, and Cry1 mRNA was in the circadian rhythm in the normal group (p ≤ 0.05), while in the periodontitis group, its circadian rhythm disappeared and the transcriptional level characteristics were changed. Interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), and interferon (IFN-γ) mRNA transcriptional level were elevated in the periodontitis group compared to the normal group. In conclusion, the mRNA transcriptional level of Bmal1, Per2, and Cry1 in alveolar bone of normal mice has circadian rhythm, but the rhythm disappears under the condition of periodontitis, and the cause of its occurrence may be related to inflammatory cytokines.

KEYWORDS:

• Periodontitis
• clock genes
• circadian rhythm
• cytokines

Acknowledgments

Thanks to the Shenzhen University for providing the conditions to perform the micro-computed tomography scanning.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

WG conceptualized and designed the study and drafted the initial manuscript. XD, MY, and TH collected the data and carried out the initial analyses. XL critically reviewed the manuscript for important intellectual content. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

Data availability statement

The data used to support the findings of this study are available from the corresponding author upon request.

Ethical approval

This study was approved by the Ethical Committee of Sichuan Hospital of Stomatology. All procedures of animal experiment were performed in accordance with the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health.

Additional information

Funding

This study did not receive any funding in any form.