| Summary: | Interactions of the Streptococcus anginosus group (SAG) with the extracellular matrix (ECM) and subsequent effects on host connective tissue and bacterial cells is proposed to be important in the initial establishment of dentoalveolar infections. The aim of this thesis was to investigate the interactions of the SAG with small leucine-rich proteoglycans (SLRPs), decorin and biglycan, from periodontal tissues and recombinant decorin and biglycan. Additional aims were to investigate the subsequent effects of the SAG on cellular components within host tissues and the influence of ECM components on bacterial phenotype. Using surface plasmon resonance, this study indicated that both commensal and pathogenic strains of the SAG interact with SLRPs but there was preferential binding toward the dermatan sulphate-substituted decorin and biglycan present in gingival tissues. In addition, commensal and pathogenic SAG isolates were shown to influence periodontal ligament (PDL) and endothelial ECM responses, including cell growth and PG synthesis. The effects on the different cell types illustrates the complexity of disease caused by the SAG, and helps to highlight the complicated roles decorin and biglycan play within the ECM. This study has also shown that potential virulence factors of the SAG, including degradative enzymes, are up-regulated following exposure to ECM components derived from PDL cells, potentially causing destruction of the host ECM and possibly inhibiting remodelling of the ECM. Overall, this thesis provides valuable information on host-SAG interactions, highlighting complex roles for SAG and SLRPs in the establishment of periapical abscesses.
|
|---|
