Background

Periodontal disease is a chronic inflammatory disease. Given its high prevalence, especially in aging population, the detailed mechanisms about pathogenesis of periodontal disease are important issues for study. Neutrophil firstly infiltrates to periodontal disease-associated pathogen loci and amplifies the inflammatory response for host defense. However, excessive neutrophil-secreted neutrophil elastase (NE) damages the affected gingival. In lung and esophageal epithelium, NE had been proved to upregulate several growth factors including placenta growth factor (PGF). PGF is an angiogenic factor with proinflammatory properties, which mediates the progression of inflammatory disease. Therefore, we hypothesize excessive NE upregulates PGF and participates in the pathogenesis and progression of periodontal disease.

Methods

In gingival epithelial cells (GEC), growth factors array demonstrated NE-increased growth factors and further be corroborated by Western blot assay and ELISA. The GEC inflammation was evaluated by ELISA. In mice, the immunohistochemistry results demonstrated ligature implantation-induced neutrophil infiltration and growth factor upregulation. By multiplex assay, the ligature-induced proinflammatory cytokines level in gingival crevicular fluid (GCF) were evaluated. Finally, alveolar bone absorption was analyzed by micro-CT images and H & E staining.

Results

NE upregulated PGF expression and secretion in GEC. PGF promoted GEC to secret IL-1, IL-6 and TNF- in GCF In periodontal disease animal model, ligature implantation triggered NE infiltration and PGF expression. Blockade of PGF attenuated the ligature implantation-induced IL-1, IL-6, TNF-and MIP-2 secretion and ameliorated the alveolar bone loss in mice.

Conclusion

In conclusion, the NE-induced PGF triggers gingival epithelium inflammation and promotes the pathogenesis and progression of periodontal disease.

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