The Role of Granzyme B in Periodontal Connective Tissue Degradation

Objectives: Periodontitis is an infectious disease resulting in inflammation within supporting tissues of teeth, with progressive attachment and bone loss. Tissue destruction during periodontitis is due to collagen-degrading matrix metalloproteinases (MMPs) released by resident cells of the periodontium in response to proinflammatory cytokines. Granzyme B (GzmB) is a serine protease produced by immune cells during chronic inflammation. GzmB is known to induce apoptosis cleave and activate pro-inflammatory cytokines and involved in extracellular matrix protein destruction. However, the role of GzmB in the the pathogenesis of periodontitis is undefined. The aim of this study is to explore the role of GzmB in progression of periodontitis. We hypothesized that level of GzmB is associated with chronic periodontitis by promoting the degradation of the connective tissues.
Methods: Human gingival fibroblasts (HGF) were treated with increasing concentrations of recombinant GzmB from (0.5-10 nM) for time periods ranging from 0 to 24 h. Time course of MMP-1 release and activity in HGF supernatants were measured by ELISA. The cytotoxicity of GzmB was assessed using an MTS cell viability assay. In a study involving human subjects, gingival crevicular fluid (GCF) samples were obtained from sites of healthy periodontium, gingivitis and periodontitis. GzmBwas quantified in the GCF by enzyme-linked immunosorbent assay (ELISA).
Results: HGFs released more pro-MMP-1 in response to GzmB. Exposure to 10 nM GzmB caused a 3 to 4-fold increase in MMP-1 activity and secretion from cultured HGFs. The cell viability assay data showed that Granzyme B had no effect on HGFs viability. GzmBlevels were higher in patients with severe periodontitis and gingivitis compared with healthy periodontium.
Conclusions: Gingival connective tissue degradation is associated with increased GzmB levels, suggesting a potential role for GzmB in the pathogenesis of periodontal disease.