Neutrophil chemokine expression in healthy and diseased periodontal tissue

Thesis (Ph.D.)--University of Washington, 2015The oral microbial community is the best-characterized bacterial community in the human host. It has been shown that clinical health and disease states are strongly correlated with the composition of the oral microbiota. As the role of dental plaque in the disease process has been investigated, it has been revealed that periodontal disease is a microbial-shift disease based on the well-characterized transition from mostly gram-positive bacteria to mostly gram-negative species, as the transition from periodontal health to disease occurs. A key component of the maintenance of healthy periodontal tissue is the recruitment of neutrophils and the associated ligands that help to signal neutrophil migration to the periodontal tissue, in particular to the junctional epithelium. In fact, the regulation of neutrophil numbers has been found to be a key component in both the maintenance of periodontal health as well as the development of disease. The subsequent pages are an examination and investigation of the role of commensal and pathogenic bacteria on the process of neutrophil migration. They will provide evidence that the presence of commensal bacteria influences the location of neutrophils and associated ligands CXCL2 but not CXCL1 when examining tissue from the root associated mesial (anterior) of the second molar to the root associated distal (posterior) of the second molar, with increased expression in the tissue associated with the mesial and distal. In addition, it will be shown that individual species of bacteria can induce a migration pattern of neutrophils and CXCL2 similar to the normal oral flora, and that this is different than the pattern expressed when no bacteria are present. Next, the examination of the periodontal pathogen P. gingivalis and two lipopolysaccharide (LPS) mutants 1587 and 1773, expanded on the findings associated with the commensal bacteria and explored the interproximal region between the teeth. This showed increased expression of neutrophils and ligands in the interproximal region, in addition to revealing that both mutants caused a decrease in neutrophil migration and CXCL6 expression. Additionally, 1587 had decreased CXCL2 expression. These results demonstrate the influence that bacteria have on neutrophil migration and associated ligand expression in the junctional epithelium and closely related tissue