Farnaz Mohajertehran - Department Oral & Maxillofacial Pathology School of Dentistry, Oral and Maxillofacial Diseases Research Center Mashhad University of Medical Sciences
Nooshin Mohtasham - Oral and Maxillofacial Diseases Research Center Mashhad University of Medical Sciences
Reza Zare - Oral and Maxillofacial Diseases Research Center Mashhad University of Medical Sciences

Lichen planus is a mucocutaneous inflammatory disease which it’s pathogenesis is not understood yet. WHO in it’s classification consider OLP (oral lichen planus) as premalignant lesion. (especially erosive type) which the premalignant and malignant potential of OLP is estimated between 9-37%. SLP (skin lichen planus) does not have malignant potential so it does not consider as as premalignant lesion as OLP does.in other hand treatment process of OLP is longer than SLP in regard to malignant changes and treatment outcome.The aim of this study was to evaluate gene expression of ROR gamma t and IL-17 in paraffin blocks of OLP and SLP lesions using Real-time RT-PCR method and investigate role of IL-17 and ROR gamma t in pathogenesis of lichen planus using new RNA extraction methods from paraffin blocks and compare with the result of peripheral white blood cells count of patients Methods & Materials: This study included 89 paraffin-embedded biopsy specimens from oral LP(ð‘› = 44) and skin LP(ð‘› = 45) blocks that were selected from the archive of Oromaxillofacial Department of Pathology in dentistry university and Imam-Reza Hospital Department of Pathology, Mashhad, Iran. The expression of ROR gamma t and IL-17 were evaluated by Real-time RT-PCR method and compared with the result of peripheral white blood cells count of patients.Results: Expression of ROR gamma t and IL-17 in OLP lesions was significantly higher than SLP lesions . comparison of Expression between subtypes of OLP (Classic and Erosive OLP) did not show any significant differences. There were no significant differences between peripheral white blood cells count and expression of the genes, but we found a high level of monocytes count in each group.Conclusions: Our findings demonstrated that the increased expression of ROR gamma t, IL-17 in LP lesions could play roles in the pathogenesis of LP. Moreover, oral LP expressing ROR gamma t, IL-17 was higher than skin LP, This may be associated with the difference in clinical behavior of the two variants of the disease and also this can explain the role of these factors in premalignant behavior of OLP lesions. Correlation of high-level monocytes with over-expression of ROR gamma t in OLP showed that monocytes may have an important role in the pathogenesis of oral lichen planus lesions and also they can be a source of producing ROR gamma t factor.

Lichen planus,OLP,SLP/CLP,ROR gamma t,IL-17,Monocytes