Oral Innate Immunity and the Role of Oral Epithelial Cells.

The oral mucosal epithelium is a complex structure that protects the underlying tissues from environmental exposure. Epithelial cells lining the mucosal surfaces of the oral cavity play an important role in innate immunity. They consist of stratified squamous epithelia that not only serve as a physical barrier but also contribute to innate immunity through the production of antimicrobial peptides and cytokines to prevent the invasion of oral pathogens. The oral cavity is constantly exposed to a great number of microorganisms. To fight against infection and maintain oral tissue homeostasis, the expression and function of cell surface receptors such as toll-like receptors (TLRs) are essential. TLRs belong to the family of pattern recognition receptors (PRRs) that recognize molecular structures categorized as "pathogen-associated molecular patterns" (PAMPs) present in microorganisms. Binding to TLRs triggers the activation of downstream signaling pathways and stimulates both innate and adaptive immune responses to suppress infection. Epithelial cells also engage distinct innate immune pathways that are implicated in the pathogenesis of oral cancer. The anticancer strategies of innate immunity include the development of an epithelial barrier, direct cytotoxicity, and presentation to various immune cells. Immune cells may have a dual impact by either promoting or suppressing cancer cell growth. Future research should investigate the factors that determine whether epithelial and immune cells promote or inhibit tumor growth. Although the mechanisms underlying this balance are not fully understood, enhancing innate immunity to combat oral infections and cancer holds potential as a strategy for early disease detection and improved treatment outcomes. Additionally, individual variations in host innate immune responses, contributing to oral cancer development, are another aspect of the complexity that requires further research.