Influence of histamine on the expression of CCL20 in human gingival fibroblasts

Background and objective: Histamine plays an important role during allergic and inflammatory reactions, and it has been suggested to influence periodontal inflammation. The aim of this study was to investigate the effects of histamine on the expression of the antimicrobial peptide C-C chemokine ligand 20 (CCL20) in human gingival fibroblasts (HGFs) when exposed to toll-like receptor (TLR) agonists.

Material and methods: Monolayers of HGFs from three different donors were exposed to histamine, alone, and in combination with Pam3CSK4 (a TLR2 agonist) or lipopolysaccharide (LPS) from Escherichia coli (a TLR4 agonist), for 2, 4, 6 or 12 h. In another experimental group, cells were pretreated with a specific histamine-1 receptor antagonist (H1R) antagonist, cetirizine. Real-time PCR analysis was performed to detect expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), CCL20 and interleukin-8 (IL8) genes. The levels of CCL20 and IL-8 protein were determined by ELISA.

Results: In HGFs, histamine induced expression of CCL20 and IL8 genes in a time-dependent manner (p < 0.05). Combined stimulation with histamine and Pam3CSK4 or LPS led to a significant amplification in expression of CCL20 and IL-8 when compared with treatment with each stimulant alone (p < 0.05), and this effect was mediated via pathways involving the H1R (p < 0.05).

Conclusion: The results of this study suggest a sensitizing effect of histamine on early innate immune responses of HGFs when simultaneously exposed to bacterial virulence factors.