Moreover, human keratinocytes exposed to Porphyromonas gingivalis (Pg) showed low expression of connexin and Grainyhead-like 2 (Grhl2), and Grhl2 conditional knockout (KO) mice showed increased epithelial infiltration of oral bacteria compared with wild-type mice, which could disrupt the epithelial barrier, thereby leading to the aggravation of periodontal disease (17). Here, GRHL2 is linked to periodontal disorder.