A Review of a Breakdown in the Barrier: Tight Junction Dysfunction in Dental Diseases

Thao Thi Do,1,* Vy Thuy Nguyen,1,* Ngoc Tran Nhu Nguyen,1 Kim Tran Thien Duong,1 Tri Ta Minh Nguyen,1 Duong Nguyen Thuy Le,1 Tin Hoang Nguyen2 1Oral Diagnosis and Periodontology Department, Faculty of Odonto-Stomatology, Can Tho University of Medicine and Pharmacy, Can Tho City, 900000, Vietnam; 2Department of Physiology, Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho City, 900000, Vietnam*These authors contributed equally to this workCorrespondence: Tin Hoang Nguyen, Department of Physiology, Faculty of Medicine, Can Tho University of Medicine and Pharmacy, 179 Nguyen Van Cu Street, An Khanh Ward, Ninh Kieu District, Can Tho City, 900000, Vietnam, Tel +84344895522, Email [email protected]: The tight junction (TJ), a type of cell-cell junction, regulates the permeability of solutes across epithelial and endothelial cellular sheets and is believed to maintain cell polarity. However, recent studies have provided conflicting views on the roles of TJs in epithelial polarity. Membrane proteins, including occludin, claudin, and the junction adhesion molecule, have been identified as TJ components. TJs are predominantly found at the stratum granulosum and stratum corneum. Although it remains unclear whether the disruption of TJs is the cause or consequence of certain dental diseases, evidence suggests that TJ dysfunction may be a crucial factor in gingival epithelial barrier impairment and the progression of oral diseases. Bacterial infection is among the most specific factors we found that may contribute to the breakdown of the epithelial barrier formed by TJs in dental diseases. Bacteria and their products may weaken the epithelial barrier by directly destroying intercellular junctions or altering the expression of junctional proteins. Additionally, they may induce the production of inflammatory cytokines, which could lead to the downregulation of TJ proteins and, consequently, impair the epithelial barrier. This review introduces a novel perspective by exploring, for the first time, the role of TJs dysfunction in the breakdown of the oral epithelial barrier and its potential link to the progression of dental diseases such as gingivitis, periodontitis, Sjӧgren syndrome, and oral squamous cell carcinoma.Keywords: epithelial barrier, gingival inflammation, Sjӧgren syndrome, oral squamous cell carcinoma, periodontitis