Immunogenic effects of enamel matrix derivative on human alveolar ridge mucosa-derived vascular endothelial cells under lipopolysaccharide stimulation

Abstract

Early peri-implant disease detection remains difficult. Enamel matrix derivative (EMD), which is used for periodontal tissue regeneration, promotes leukocyte chemotactic factor and adhesion molecule expression in vascular endothelial cells. We hypothesized that stimulating vascular endothelial cells with EMD would induce an inflammatory response in the peri-implant mucosa, enabling early peri-implant infection detection. To verify this hypothesis, we assessed the intercellular adhesion between human alveolar ridge mucosa-derived vascular endothelial cells (ARMEC) stimulated with lipopolysaccharide (LPS) and EMD and human periodontal ligament-derived vascular endothelial cells (PDLEC). Leukocyte chemotactic factors and cell adhesion molecules were investigated and we established an experimental model of peri-implant disease by stimulating ARMEC (representing the peri-implant mucosa) with Porphyromonas gingivalis-derived LPS. ARMEC and PDLEC were obtained from patients (n = 6) who visited the Nippon Dental University Niigata Hospital. The cells were divided into four subcategories, each cultured with: LPS (1 µg/mL), EMD (100 µg/mL), LPS + EMD, and pure medium. Cell viability, leukocyte chemotactic factor (interleukin-8: IL-8), adhesion molecules (intercellular adhesion molecule-1: ICAM-1), tight junction protein gene expression (zonula occludens-1: ZO-1 and Occludin), and transendothelial electrical resistance (TEER) was then determined. LPS reduced ARMEC viability, whereas simultaneous stimulation with EMD improved it. LPS and EMD stimulation enhanced IL-8 and ICAM-1 gene expression, suppressed TEER, and decreased ZO-1 and Occludin expression levels compared to that with stimulation with LPS alone. EMD stimulates leukocyte migration, increase vascular permeability, and trigger an immune response in the peri-implant mucosa, thus facilitating the early detection and treatment of peri-implant disease.

Keywords: Alveolar ridge mucosa; Early diagnosis; Enamel matrix proteins; Peri-implantitis; Vascular endothelial cells.