mRNA expression and localization of LPS-induced β-defensin isoforms in rat salivary glands

β-defensins are small, cationic peptides with broad-spectrum antimicrobial activity that are produced by mucosal epithelia. However, little is known about the expression of β-defensins in the major salivary glands. The purpose of this study was to characterize expression of rat β-defensin-1 (RBD-1) and -2 (RBD-2) mRNA within the major salivary glands together with the effect of injection of intraductal lipopolysaccharide (LPS) on that expression. β-defensin mRNA expression was quantitated by RT-PCR in salivary gland tissues and salivary acinar and striated duct cells collected by laser captured microdissection. RBD-1 and -2 were expressed in the parotid gland, the submandibular gland, and the sublingual gland. β-defensins were expressed in both the acinar and striated duct cells of the major salivary glands. Intraductal injection of LPS increased expression of RBD-1 and -2 mRNA, which peaked at 12 hrs. These results suggest that salivary cells (acinar and striated duct cells) have the potential to produce β-defensins.