LL37 induces VEGF expression in dental pulp cells through ERK signalling

To examine the in vitro effects of LL37 on the expression of vascular endothelial growth factor (VEGF) in human pulp cells and to identify the intracellular signalling pathway involved. Methodology: Pulp cells at passage 6 were treated with 10 μg mL^-1 synthesized LL37, and an inhibition assay was performed with MAPK or NF-κB inhibitors to determine the possible signalling pathway. VEGF mRNA, VEGF protein and phosphorylated ERK1/2 levels were determined by real-time PCR, ELISA and Western blot, respectively. Data were analysed using t-tests. Results: LL37 significantly increased both the mRNA and protein levels of VEGF in pulp cells (P < 0.01). However, pre-treatment with an ERK kinase inhibitor suppressed these increases. Furthermore, the inhibitor blocked LL37-induced ERK1/2 phosphorylation. Conclusions: LL37 activated the ERK pathway to boost VEGF secretion from human pulp cells. Because of this angiogenic effect and its reported induction of pulp cell migration and antimicrobial activity against cariogenic bacteria, LL37 may be applicable as a pulp capping material.