TLR3 and oral lichen planus: Among the enriched GO terms identified in the epithelial dataset and mucosa partial set, defense responses to both gram-positive and negative bacteria, positive regulation of antibacterial peptides active against gram-positive bacteria, positive regulation of antibacterial peptide production, cellular response to lipopolysaccharide (LPS), Toll-like receptor 3 signaling pathway, and antigen processing and presentation of exogenous peptide antigen via MHC class II (Fig 2, S6 and S8 Tables) indicated potential microbial infection in OLP.