A study on possible roles of granulocyte neutral proteinases and the control mechanism of their activities in the process of periodontal breakdown

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To clarify the role of host-derived lysosomal proteinases in the mechanism of periodontal breakdown, cathepsin G and medullasin, two major serine proteinases, were investigated. In gingival crevicular fluid (GCF) obtained from periodontitis patients, almost all activities of both enzymes were not detected, while the amounts of both enzymes determined by enzyme-linked immunosorbent assay increased with increasing GCF volume, indicating the participation of the enzymes in the progression of periodontitis. The reason why their activities were lost in GCF is suggested that they were blocked by their specific serum-derived proteinase inhibitor, especially alpha_1-proteinase inhibitor, since immunoblotting analyzes of GCF using each enzyme and alpha_1-proteinase inhibitor revealed a weak protein band of the respective enzyme and the inhibitor alone and a strong band of the complex of those. In experimental gingivitis of volunteers induced by refraining from all oral hygiene measures for 21 d … More ays, a remarkable increase of these enzymes in GCF were shown prior to the detection of inflammation monitored by various clinical parameters, suggesting the involvement in the development of inflammation. In inflamed gingival tissues, these enzymes were restricted in neutrophils and macrophages and concentrated especially in the vicinity of pocket epithelium partly with degranulation extracelluarly. This finding suggests the participation of these enzymes in direct degradation of host tissues besides the host-defensive mechanism against bacterial pathogens. Moreover, purified enzymes injected into rabbit gingivae caused inflammatory response characterized by noticeable injury to vessels and mild infiltration of inflammatory cells including neutrophils and macrophages. The function of the enzymes, however, were completely lost with the treatment by their specific inhibitor, alpha_1-proteinase inhibitor or alpha_1-antichymotrypsin. From the findings in this study, cathepsin G and medullasin are present in GCF and gingival tissue and participated in the host-defensive mechanism modulated by serum-derived proteinase inhibitors. Once the enzyme-inhibitor balance is lost, these two enzymes conversely play a destructive role against periodontal tissues. Less