Oral Lichen Planus: Pro and AntiInflammatory Factors Influence Clinical Outcomes

Objectives: To examine the immunohistochemical expression of CD4+ and CD8+ lymphocytes, transcription factor NF-êB (potent pro-inflammatory) and CD163+ macrophages and regulatory T cells (Treg) (anti-inflammatory, immune-suppressor factors) in hyperkeratotic (H) and erosive (E) oral lichen planus (OLP) and to relate it to clinical parameters. Methods: The study comprised cases of H-OLP (N=23) and E-OLP (N=26). The expression of CD4+, CD8+ lymphocytes, NF-kB and CD163+ macrophages was assessed as the % of positive cells from the total number of inflammatory cells. The expression of CD4+ and CD8+ was also assessed as the % of positive lymphocytes within the most stained areas ("hot spots") of inflammatory infiltrate - %focal. Expression of NF-êB (%) was also assessed within the lining epithelial cells. Treg (Foxp3+ phenotype) cells were scored as the mean number of cells at the interface of the epithelium-inflammatory infiltrate. The results of the immunnostains were assessed for statistical associations with the clinical parameters of OLP type (hyperkeratotic, erosive), symptoms (discomfort, sensitivity and pain) and reaction to treatment (good vs. partial) using t-test and Pearson's correlation tests. Results: %focal CD4+ was associated with presence of symptoms and partial response to treatment (p=0.001 and p=0.012, respectively). Nuclear NF-kB was only found in the epithelial cells. Percent of CD163+ cells was significantly higher in the E-OLP (47.7%+24.7%) than in H-OLP (31.4+18.6%) (p=0.017). Treg were associated with partial response to treatment (p=0.007). Conclusion: The interplay among the pro- and anti-inflammatory factors may control the type of OLP, the clinical symptoms and response to treatment.