Expression of nucleotide-binding oligomerization domain 1 and 2 in oral lichen planus

Abstract Background/Purpose Oral lichen planus (OLP) is a chronic inflammatory disease of oral mucosa. The present study investigated the expression of nucleotide-binding oligomerization domain (NOD), a pivotal sensor protein of the innate immune system, in OLP. Materials and methods Oral mucosal biopsies were collected from 20 patients with OLP and 6 individuals with normal oral mucosa (NOM). The expression of NOD1 and NOD2 was determined using RT-PCR and immunohistochemistry in OLP and NOM samples. Results The mRNA expression of NOD1 and NOD2 was significantly higher in the OLP group than in the NOM group. The protein expression of NOD1 was marginally upregulated in all mucosal layers in the OLP group compared with that of the NOM group; however, the differences were not significant. The expression of NOD2 was elevated in infiltrating lymphocytes of the submucosal layer in the OLP group compared with the NOM group, but was undetected in other inflammatory disease, inflammatory fibrous hyperplasia (IFH). This study revealed the upregulation of NOD2 mRNA and protein in the OLP group, but not in the NOM group. Conclusion These findings suggest that NOD2 may play an important role in the pathogenesis of OLP and represents a new diagnostic and treatment target.