IL-8 degradation by Porphyromonas gingivalis proteases

Gingival epithelial cells are the primary barrier to infection by periodontal pathogens. The production of chemotactic cytokines, including interleukin-8 (IL-8), is one mechanism the host uses in response to infection. In this study it was found that both gingival and oral epithelial cells produced IL-8, but after infection with the periodontal pathogen Porphyromonas gingivalis, accumulation of the cytokine could not be detected. Northern analysis established that infected epithelial cells still expressed IL-8 mRNA, suggesting that the cytokine was destroyed after secretion. Incubation of IL-8 with P. gingivalis cells resulted in rapid loss of the cytokine; however, in the presence of a protease inhibitor the loss was significantly retarded, indicating that IL-8 was degraded by P. gingivalis proteases.