IFNG and periodontitis: Accordingly, it has been shown that a selective PAR2 agonist (SLIGRL) causes periodontitis in rats through a mechanism involving prostaglandin release and MMP activation [65] and that PAR2-knockout mice infected with Porphyromonas gingivalis have decreased levels of proinflammatory mediators, such as prostaglandin E2, interferon-gamma, IL-1beta, and IL-6, and less alveolar bone loss when compared to wild-type animals [6].