Confocal immunolocalization of VE-cadherin- and CXC chemokine-expressing endothelial cells in periapical granulomas

Aim To determine whether endothelial cells (ECs) in periapical granulomas can express vascular endothelial (VE)‐cadherin, CXCL8 and CXCL10 by examining with two‐colour confocal laser scanning microscope. Methodology Periapical lesions were surgically removed from patients with chronic periapical periodontitis (n = 20), and the paraffin‐embedded sections were prepared after being fixed with cold acetone. The 7‐μm‐thick sections were stained with haematoxylin–eosin and then examined pathologically using a light microscope. The lesions diagnosed as periapical granulomas (17 specimens) were analysed further using immunofluorescence and antibodies specific for human VE‐cadherin, CXCL8, and CXCL10. The slides were carefully examined using a confocal laser scanning microscope. The numbers of positive ECs were counted, and the comparison between VE‐cadherin‐positive ECs and CXCL8 or CXCL10 was assessed statistically using one‐way ANOVA followed by a Student–Newman–Keuls test. Results The expression of CXCL8 and CXCL10 by ECs was detected in 60.4 ± 13.4 and 67.2 ± 13.9%, respectively. However, the percentage of VE‐cadherin‐expressing ECs was 40.4 ± 10.5%, which was significantly lower (P < 0.01) than CXCL8 and CXCL10‐expressing ECs. Two‐colour immunofluorescence staining revealed that ECs co‐expressed VE‐cadherin and CXCL8 (37.4 ± 14.1%) or CXCL10 (39.1 ± 13.8%). Conclusions VE‐cadherin expression in ECs was lower than CXCL8 and CXCL10, suggesting that inflamed ECs in periapical granulomas could increase vascular permeability and that leukocyte chemotaxis mediated by ECs might occur. These findings may suggest the possibility that ECs could play a pivotal role in cell recruitment in periapical granulomas.