Zeng Q, et al. - Herein, an inquiry was performed with regard to the potential role of the toll-like receptor 4 (TLR-4) pathway in overproduction of CC chemokine ligand 2 (CCL2) in oral lichen planus (OLP) lesions. Increased TLR-4 expression played a role in the upregulated expression of CCL2 in the epithelium of OLP lesions. This was indicative of oral bacteria taking part in the pathogenesis of OLP via the TLR-4 pathway.