Toll like receptor-2 expression is increased in oral lichen planus

Objectives: Oral lichen planus (OLP) is a chronic inflammatory condition characterized by varied clinical presentations. Oral mucosal lichenoid reactions occur following dental restorations or the use of certain systemic drugs, diagnosed clinically as idiopathic OLP. Considerable data support a concurrent occurrence of OLP and candidiasis. The toll like receptors (TLRs) constitute an important group of pattern recognition receptors that bind conserved pathogen associated molecular patterns on the microbes. There are ten TLRs in humans expressed on immune cells and epithelial cells. TLRs act singly or in combination to recognize specific microbial ligands. Soluble forms of TLR-2 in the serum and milk are thought to play a role in sequestrating microbes. TLR-2 and TLR-4 are important in the recognition of Candida albicans. In this study, our objectives were to investigate the presence of TLR-2 and TLR-4 in human saliva and to compare the salivary expressions between normal individuals and patients with OLP.

Methods: Unstimulated whole saliva was collected from 15 patients clinically diagnosed with OLP and equal number of age and sex matched controls in accordance with the Institutional Review Board at Indiana University Purdue University at Indianapolis. The salivary TLR-2 and TLR-4 was detected by immunoblot analysis. Images acquired by Kodak Gel logic 440 imaging systems were quantitated using Kodak 1D image analysis software.

Results: Our results show that sTLR-2 and sTLR-4 can be detected in human saliva and that the level of sTLR-4 is higher. Importantly, the sTLR-4 is significantly decreased and sTLR2 is moderately increased in the saliva of patients with OLP.

Conclusion: We demonstrate for the first time the presence of soluble forms of the innate immune associated proteins TLR-2 and TLR-4 in normal human saliva. Variations of these proteins in the saliva may be associated with oral mucosal diseases such as OLP.