Diabetes-related Molecules affect Expression of Epithelial Antimicrobial Peptides in Keratinocytes

Objective: Human beta-defensin(hBD)s and Cathelicidin/LL-37 (LL-37) belong to a group of antimicrobial peptides expressed in oral epithelial cells. Diabetes is a risk factor in oral infections including periodontitis. The hyperglycemia, insulin and adiponectin deficiency/insensitivity may affect hBDs expression. Therefore, the present study investigated the effect of glucose, insulin and adiponectin on the expression of hBD-1,-2 and -3 and LL-37. Methods: Keratinocyte cell line, HaCaT cells were grown in DMEM supplemented with 10% fetal bovine serum. To examine the effect of the combination of glucose, insulin and adiponectin on the expression of hBDs mRNAs and proteins, the cells were incubated with 5.5, 10, 15 and 50mM of glucose and/or with 10 and 20ƒÝU/ml of insulin and/or with 3, 10 and 30ƒÝg/ml of adiponectin for 12hr. The cells incubated without glucose insulin, or adiponectin was used as controls. Expression of hBD1~3 and LL-37 in HaCaT cells were observed by RT-PCR and quantitative RT-PCR using TaqMan probes. Fold induction represent means °" SD of triplicate experiments. P values were calculated by student's t test. Results: No significant differences are observed in the expression of hBDs and LL-37 between any concentrations of glucose. Expression levels of hBD-2,-3 and LL-37 in 150nM of insulin were significantly higher than those in the controls. Expression levels of hBDs and LL-37 in 3ƒÝg/ml of adiponectin were significantly higher than those in the controls. Combination of 5.5mM of glucose, 150nM of insulin and 3ƒÝg/ml adiponectin stimulated the highest levels of the hBD-2, -3 and LL-37 in each experiment. Conclusion: The results indicated that optimal concentration of glucose insulin and adiponectin might be needed to maintain a high expression level of hBDs and LL-37.