Methods : ECM genes expression pattern during healing phase in rat experimental periapical lesion were analyzed by DNA microarray. Mouse osteoblastic cells, MC3T3-E1, were treated with IL-1α (0-10 ng/ml) for 48 h, and cells were seeded in ECM (laminin or fibronectin)-coated culture plates. After 1 h incubation, non-adherent cells were removed and adherent cells were stained with crystal violet. Also, cells were treated with IL-1α for 48 h, and total cell lysates were collected to monitor integrin subunits expression by Western blotting. In addition, to investigate the effects of IL-1α for osteogenesis, cells were pre-treated with IL-1α (0.1 ng/ml), seeded in ECM-coated plates, and cultured for 5 weeks. Calcium productivity was monitored by von Kossa staining.
Results : During periapical healing phase, laminin γ2 gene expression was up-regulated dramatically compared to inflammation phase. IL-1α enhanced MC3T3-E1 attachment to a laminin-coated plate significantly compared to that of fibronectin or poly-D-lysine-coated plates (p<0.05). Also, IL-1α enhanced integrin α3 protein expression, but not α6, β1, β4 (p<0.05). Furthermore, IL-1α enhanced calcium production in laminin-coated plates compared to that of other coated plates.
Conclusion: Our findings suggest that IL-1α may enhance integrin α3 expression and attachment to laminin for inducing osteogenesis in osteolbasts during periapical healing.