title: The presence of bacteria within tissue provides insights into the pathogenesis of oral lichen planus.
abstract: Oral lichen planus (OLP) is a chronic T cell-mediated mucocutaneous disease of unknown etiopathogenesis. Although various antigens have been considered, what actually triggers the inflammatory response of T cells is unknown. In the present study, we propose that intracellular bacteria present within tissues trigger T cell infiltration and provide target antigens. Sections of OLP (n = 36) and normal (n = 10) oral mucosal tissues were subjected to in situ hybridization using a universal probe targeting the bacterial 16S rRNA gene and immunohistochemistry with anti-CD3, anti-CD4, anti-CD8, and anti-macrophage-specific antibodies. Bacteria were abundant throughout the epithelium and the lamina propria of OLP tissues, which exhibited positive correlations with the levels of infiltrated CD3(+), CD4(+), and CD8(+) cells. Furthermore, bacteria were detected within the infiltrated T cells. Pyrosequencing analysis of the mucosal microbiota from OLP patients (n = 13) and control subjects (n = 11) revealed a decrease in Streptococcus and increases in gingivitis/periodontitis-associated bacteria in OLP lesions. Using the selected bacterial species, we demonstrated that certain oral bacteria damage the epithelial physical barrier, are internalized into epithelial cells or T cells, and induce production of T cell chemokines CXCL10 and CCL5. Our findings provide insights into the pathogenesis of OLP.
authors.affiliation: Departments of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea.
authors.forename: Yun Sik
authors.initials: YS
authors.lastname: Choi
authors.affiliation: Departments of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea.
authors.forename: Yunji
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Oral Pathology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea.
authors.forename: Hye-Jung
authors.initials: HJ
authors.lastname: Yoon
authors.affiliation: Departments of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea.
authors.forename: Keum Jin
authors.initials: KJ
authors.lastname: Baek
authors.affiliation: Departments of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea.
authors.forename: Jehan
authors.initials: J
authors.lastname: Alam
authors.affiliation: Oral Medicine and Oral Diagnosis, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea.
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Park
authors.affiliation: Departments of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea.
authors.forename: Youngnim
authors.initials: Y
authors.lastname: Choi
mesh_terms: D000328:Adult; D000368:Aged; D001419:Bacteria / Q000378:metabolism*; D018925:Chemokines / Q000378:metabolism; D004705:Endocytosis; D004847:Epithelial Cells / Q000382:microbiology; D005260:Female; D006801:Humans; D017676:Lichen Planus, Oral / Q000382:microbiology* / Q000473:pathology; D008297:Male; D064307:Microbiota; D008875:Middle Aged; D008954:Models, Biological; D009092:Mucous Membrane / Q000382:microbiology / Q000473:pathology; D010802:Phylogeny; D013601:T-Lymphocytes / Q000382:microbiology
chemical_list: D018925:Chemokines