Original Article

Citation: Experimental & Molecular Medicine (2016) 48, e223; doi:10.1038/emm.2015.127
Published online 25 March 2016

Chronic stress accelerates ligature-induced periodontitis by suppressing glucocorticoid receptor-α signaling
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Huaixiu Lu1, Minguang Xu2, Feng Wang1, Shisen Liu1, Jing Gu1, Songshan Lin1 and Lisheng Zhao3

  1. 1Department of Stomatology, Navy General Hospital, Beijing, China
  2. 2Department of Medical Engineering, The Second Artillery General Hospital PLA, Beijing, China
  3. 3Department of Stomatology, Chinese PLA General Hospital, Beijing, China

Correspondence: Dr H Lu, Department of Stomatology, Navy General Hospital, No. 6, Fucheng Road, Beijing 100048, China. E-mail: huaixiulu@163.com

Received 21 August 2015; Revised 27 November 2015; Accepted 6 December 2015

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Abstract

Periodontitis is a common chronic inflammatory disease. Recent studies have shown that chronic stress (CS) might modulate periodontal disease, but there are few models of CS-induced periodontitis, and the underlying mechanisms are unclear. The present study established a rat model of periodontitis associated with CS induced by nylon thread ligatures. The severity of periodontitis was evaluated in this model by radiographic and pathological examination. The inflammatory reaction indicated by the elevated serum levels of interleukin (IL)-1β, IL-6 and IL-8 was assessed by enzyme-linked immunosorbent assay. Toll-like receptor-4 (TLR4) and glucocorticoid receptor-α (GR-α) expressions were detected by reverse transcriptase-PCR and western blotting. Open-field tests and serum corticosterone were used to evaluate CS. The results showed that CS induced behavioral changes and increased corticosterone levels of the animals with periodontitis. CS stimulation markedly increased alveolar bone loss, periodontal pocket depth and the number of plaques. It also enhanced the inflammatory reaction. These results suggest that CS accelerated the ligature-induced pathological changes associated with periodontitis. Further analysis of the mechanisms involved showed that GR-α expression was significantly downregulated in periodontal tissues of the animals undergoing CS. Blocking GR-α signaling in lipopolysaccharide and corticosteroid-treated human periodontal ligament fibroblast cells in vitro significantly upregulated the expression of p-Akt (protein kinase B) and TLR4, promoted nuclear factor-κB activity and increased levels of IL-1β, IL-6 and IL-8. This research suggests that CS might accelerate the pathological progression of periodontitis by a GR-α signaling-mediated inflammatory response and that this may be a potential therapeutic target for the treatment of periodontal disease, particularly in patients with CS.