Spirochete Induced OncostatinM From Neutrophils Stimulates Fibroblast Matrix-Metalloprotease Activity

Objectives: Innate immune cells secrete a versatile cytokine, oncostatin M (OSM), that is elevated in many inflammatory conditions which can regulate signaling processes and matrix metalloprotease (MMP) activity. The contribution of the stromelysin group of MMPs is not well understood, despite evidence of the elevation of some members of this group in periodontal disease. Our objective is to characterize the capacity of T. denticola to induce OSM from neutrophils and secondarily investigate how OSM influences stromelysin production from gingival fibroblasts and correlate these molecules in clinical saliva specimens.
Methods: Peripheral blood neutrophils were isolated from healthy donors using density gradient methods. Human gingival fibroblasts (HGF) were isolated from healthy discarded gingival tissue. Neutrophils were exposed to T. denticola 35405 followed by collection of conditioned media and cell samples. OSM gene expression (RT-PCR) and protein levels (ELISA) were quantified. HGFs were exposed to purified OSM or T. denticola conditioned neutrophil media, followed by collection of culture media or cell samples. Stromelysin protein levels (ELISA) and gene expression (RT-PCR) was measured. Saliva samples were collected from clinically healthy ( n=3) or periodontal disease subjects ( n=4).
Results: OSM gene expression (p<0.05, n=3) and protein secretion (p<0.05, n =3) was increased following exposure of blood neutrophils to T. denticola. Exposure of HGFs to purified OSM or T. denticola conditioned neutrophil media increased stromelysin secretion and gene expression. Saliva samples from subjects with periodontal disease demonstrated elevated stromelysin and OSM levels compared to healthy controls, which correlated with the presence of T. denticola in saliva
Conclusions: T. denticola induces OSM production from neutrophils, which can secondarily increase stromelysin MMP production from gingival cells, which may contribute to periodontal tissue damage. Elevation of stromelysin and OSM in saliva from periodontal disease subjects with concomitant T. denticola presence suggest spirochetes may drive production from neutrophils.