IL-22 induces b-defensins and co-localizes with hBD-3 to basal epithelium

Human beta-defensins (hBDs) belong to a group of antimicrobial peptides expressed mainly in epithelial cells, including oral and skin keratinocytes. Interleukin 22 (IL-22) is an effector cytokine produced by T cells and mediates crosstalk between the immune system and epithelial cells. Objectives: To investigate the effects of IL-22 on the expression of hBD-2, -3 mRNA in human oral epithelial cells (HOECs) and conduct in-situ localization of hBDs, IL-22 and IL-22 receptor (IL-22r) expression in normal and diseased oral tissues. Methods: Primary HOECs were incubated with recombinant human IL-22 (rhIL-22) at various concentrations (0, 3, 10, 30, 100ng/ml) for 18h. Fold increase in mRNA expression of hBD-2 and -3 in HOECs was quantified by real-time PCR. Individual experiments were done in triplicate. HBD-2, -3, IL-22 and IL-22r were localized (antibodies: hBD-2 [SantaCruz], hBD-3, IL-22r [Novus Biologicals], IL-22 [PeproTech]) in oral lichen planus (LP), an inflammatory disease that affects the oral mucosa and is associated with infiltration of inflammatory cells in the subepithelial layer of connective tissue. Results:IL-22 upregulated hBD-2 and -3 mRNA in a dose dependent manner, with peak induction at 100ng/ml. HBD-2 was 6 fold and hBD-3 was 7 fold higher than baseline control HOECs. Confocal microscopy analysis of LP revealed that hBD-3 was localized to basal keratinocytes and overexpressed when compared to controls, while hBD-2 appeared in suprabasal areas. IL-22 co-localized to the same basal keratinocytes as hBD-3 and IL-22 receptor expression was found associated with these cells as well. Conclusion:These results indicate that IL-22 upregulates hBD-2 and -3 mRNA in oral epithelial cells, and co-localizes with hBD-3 to the basal epithelium in oral lichen planus. Supported by NIH/NIDCR R01DE015510 and R01DE016334.