Campylobacter concisus is an emerging bacterial pathogen that may play a role in the development of inflammatory bowel disease and oral inflammatory conditions such as periodontal disease. To elucidate the role and pathogenic mechanisms of C. concisus in contributing to oral inflammation, this study examined the production of IL-1 family proinflammatory cytokines IL-18 and IL-1 beta in oral epithelial cells induced by C. concisus strains using enzyme-linked immunosorbent assay (ELISA), Western-blot and quantitative real-time PCR. C. concisus increased the mRNA levels of IL-18 and IL-1 beta in oral epithelial cells. Furthermore, a large amount of IL-18 in the supernatants of oral epithelial cells infected with C. concisus strains was detected by ELISA, and various experiments demonstrated that this positive signal was derived from C. concisus bacterium. The findings that C. concisus upregulated IL-18 and IL-1 beta in oral epithelial cells from this study support a role of C. concisus in oral inflammatory diseases. Furthermore, the finding that C. concisus released a molecule that was strongly cross-reactive to anti-human IL-18 monoclonal antibodies suggests that in future studies examining cytokines induced by bacterial microbes, a bacterium control should be included. (C) 2019 Elsevier Inc. All rights reserved.