Upregulation of TRPA1 and reduction of NF-κB translocation could be part of the immunomodulatory process during primary tooth inflammation

Transient receptor potential ankyrin 1 (TRPA1) is expressed on neurons and immune and endothelial cells, and acts as a chemosensor that is activated by bacterial components and endotoxins. This study aimed to better understand how TRPA1 responds to inflammation induced by bacterial-related stimuli during dental caries. The pulp of 40 primary teeth and 46 permanent teeth were categorized into three stages of carious progression: intact dentin, exposed dentin and exposed pulp. We measured the percentages of cells with NF-κB nuclear translocation to verify the severity of inflammation, and then assessed TRPA1 expression by immunofluorescence technique in the pulpal horn, subodontoblastic and mid-coronal regions of the dental pulp samples at various stages of caries. We found NF-κB nuclear translocation gradually reduced during the progression of caries in all three areas of the dental pulp in both primary and permanent teeth. TRPA1 was gradually upregulated in the pulp of primary teeth as caries progressed, but did not significantly vary during caries in the pulp of permanent teeth. This study of TRPA1 expression demonstrates primary and permanent teeth exhibit distinct responses when undergoing carious infection.