Oral Epithelial Barrier Integrity: a Humanized Immunohistochemical Study of Junctional Proteins in Oral Diseases

Abstract

Introduction: The oral epithelial barrier is crucial for the control of microbial invasion and immune response to maintain mucosal homeostasis. Impaired epithelial barrier integrity has been associated with the pathogenesis of inflammatory, potentially malignant, and malignant oral diseases.

Objective: To examine the immunohistochemical expression of oral epithelial barrier proteins, including E-cadherin, Claudin-1, Occludin, and ZO-1, across inflammatory, potentially malignant, and malignant oral lesions.

Methods: This descriptive cross-sectional study was conducted at the Khyber Medical University, Peshawar, Pakistan, from November, 2025 to April, 2026. Non-probability consecutive sampling was used to enroll a total of 120 participants. Histopathological and immunohistochemical analysis of oral tissue samples was performed for the expression of E-cadherin, Claudin-1, Occludin, and ZO-1. SPSS version 27.0 was used for statistical analysis.

Results: 120 participants were analyzed. The decrease in expression of E-cadherin was found in 61.7% of the tissue samples, followed by ZO-1 (59.2%), Claudin-1 (55.8%), and Occludin (51.7%). All four epithelial barrier proteins were found to be significantly different between the study groups, with statistically significant results for E-cadherin (p < 0.001), Claudin-1 (p = 0.002), Occludin (p = 0.011) and ZO-1 (p < 0.001). These results suggest that there is a progressive decrease of the expression of epithelial barrier proteins in inflammatory lesions, potentially malignant lesions, and malignant lesions of the oral cavity.

Conclusion: Oral epithelial barrier dysfunction is closely linked to disease progression and could serve as a useful biomarker and therapeutic target. Restoration of epithelial integrity may be beneficial for disease prevention and clinical outcomes with strategies.