VIP Inhibits P. gingivalis LPS-induced IL-18 and IL-18BPa in Monocytes

• Published in: Journal of dental research 2007-09, Vol.86 (9), p.883-887
• Main Authors: Foster, N., Andreadou, K., Jamieson, L., Preshaw, P.M., Taylor, J.J.
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Cell Line; Dentistry; Humans; Inflammation Mediators - pharmacology; Inflammation Mediators - physiology; Intercellular Signaling Peptides and Proteins - biosynthesis; Interleukin-18 - antagonists & inhibitors; Interleukin-18 - biosynthesis; Lipopolysaccharides - pharmacology; Monocytes - drug effects; Monocytes - immunology; Monocytes - metabolism; Porphyromonas gingivalis - chemistry; Vasoactive Intestinal Peptide - pharmacology; Vasoactive Intestinal Peptide - physiology
• ISSN: 0022-0345; 1544-0591
• DOI: 10.1177/154405910708600915

IL-18 is a pro-inflammatory cytokine that is important in the regulation of T-cells and is elevated in inflammatory disorders such as periodontal disease. Vasoactive intestinal peptide (VIP) modulates immune responses to the periodontal pathogen Porphyromonas gingivalis (Pg). Our objective was to investigate the effect of Pg LPS on IL-18 and its natural inhibitor, IL-18 binding protein (IL-18BPa), in human monocytes, and the effect of VIP on this system. We demonstrated that Pg LPS induced both IL-18 and IL-18BPa secretion in cultures of the human monocytic cell line THP-1, as measured by specific ELISA. The addition of antibodies to IL-18BPa to the stimulated THP-1 cultures resulted in increased levels of free IL-18, indicating a specific interaction between IL18 and IL-18BPa in this system. VIP (10−8M) inhibited both IL-18 and IL-18Bpa secretion by stimulated monocytes. We conclude that IL-18 and IL-18BPa secretion by monocytes is part of the immune response to Pg, and that VIP can inhibit this process.