PTGS2 and periodontitis: The activation of the JAK-STAT pathway induced by the Porphyromonas gingivalis lipopolysaccharide (LPS) and nicotine was shown to increase the expression of cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and proinflammatory cytokines in osteoblasts, thus further accelerating periodontitis progression [69, 70].