Fig. 2

Signaling pathways in inducible expression of HST in epithelial cell. (AEP acquired enamel pellicle, LPS lipopolysaccharide, MAPK mitogen-activated protein kinase, MMP matrix metalloproteinases, ROS reactive oxygen species) [24]. In the mechanism depending on protein kinases (MAPK), HST specifically assimilate with membrane receptors via a series of mechanisms inducing the production of reactive oxygen species (ROS) [25]. HST by a way of non-lytic outflow from cell lead to the release of ATP and inhibition of the main metabolic pathways (i.e. cellular respiration) [26]. Together with reactive oxygen species, HST release histamine from mast cells [27] and lead to DNA damage [28]. HST have a function of chelating transition metal ions (Cu²⁺ and Zn²⁺), which may be of importance for the protection of tooth enamel and antimicrobial protection