Enhanced T-cell proliferation and IL-6 secretion mediated by overexpression of TRIM21 in oral lesions of patients with oral lichen planus

Backgrounds To explore the expression and functions of the tripartite motif-containing protein 21 (TRIM21) in oral lichen planus(OLP) lesions. Methods Paraffin sections of buccal mucosa samples from 15 cases of reticular oral lichen planus (OLP) patients and 10 healthy controls were used for immunohistochemistry to determine expression and distribution of TRIM21. Buccal mucosae from 11 OLP patients and seven healthy controls were analyzed by qPCR to quantify its gene expression. Peripheral blood mononuclear cells and CD3+ cells from four pairs of age- and sex-matched OLP patients and healthy controls were isolated for immunocytochemistry and culture. Following lentivirus-mediated overexpression of TRIM21 gene in CD3+ cells, CCK-8 was applied to evaluate cell proliferation. Cytokines including IL-2, IL-4, IL-5, IL-6, IL-10, TNF-alpha, and IFN-gamma in the supernatants were measured by the cytometric bead array and verified by ELISA. Results A larger number of TRIM21-positive cells infiltrating the lamina propria were observed in OLP lesions by immunohistochemistry than those of healthy controls. Significantly higher transcription of TRIM21 was revealed by qPCR. TRIM21 overexpression in CD3+ cells significantly enhanced the proliferation and IL-6 secretion in CD3+ cells from 12 to 72 hours. Conclusion Overexpressed TRIM21 in OLP may be a primary proinflammatory molecule rather than a secondary and inducible regulatory factor in immunopathogenesis of OLP.