Immunohistochemical expression of TLR4 and TLR9 in various grades of oral epithelial dysplasia and squamous cell carcinoma, and their roles in tumor progression: a pilot study.

Toll-like receptors (TLRs) play an essential role in the activation of innate immunity. TLRs are expressed in B-lymphocytes, monocytes, dendritic cells and epithelial cells. We examined the immunohistochemical expressions of TLR4 and TLR9 in various grades of oral epithelial dysplasia (OED), oral squamous cell carcinoma (OSCC) and normal oral mucosa (NOM) to determine the association between TLR4 and TLR9 in the progression of lesions from dysplasia to carcinoma. Expressions of TLR4 and TLR9 were assessed using immunohistochemistry (IHC) on paraffin embedded tissue blocks of various grades of OED (28 cases), OSCC (27 cases) and NOM (10 cases). Expression of TLR4 was high in all grades of OED and OSCC. Expression of TLR9 was high in well differentiated squamous cell carcinoma and moderately differentiated squamous cell carcinomas, and moderate to low in poorly differentiated squamous cell carcinomas. Although expression was high in case of TLR4, it was not statistically significant. Expression of TLR9 was statistically significant. In OED, expression of TLR9 was less than that of TLR4. Our results indicated that the pattern of expression of TLR4 and TLR9 increased significantly from mild to severe dysplasia compared to controls. Expression of TLR4 and TLR9 reflects progression of OED to OSCC, which suggests that TLR may play a role in tumorigenesis and that it could be used as a target for OSCC prevention and therapy in the future.