Immunolocalization of laminin and integrin in junctional epithelium after gingivectomy

Objective: The expression patterns of adhesive proteins and extracellular matrix proteins in regenerating gingival epithelium after gingivectomy are unknown. The aim of this study was to examine the expression of laminin 1, laminin g₂ (a specific component of laminin 5), integrin b₄ and integrin a₃ in the regenerating gingival epithelium in order to understand this wound healing mechanism during reconstitution of the sulcular environment. 

Methods: Sixty 8 wk old male ICR mice were used in this study. The palatal gingiva of the right and left maxillary first to second molars were excised and the regenerating tissues were examined 1, 3, 5, 7 and 14 days later. Fresh non-fixed and non-decalcified frozen sections were prepared and stained using immunofluorescence.

Results: At 1 day post-surgery, intense expression of laminin g₂, integrin b₄ and integrin a₃ was distinct in the frontal margin of the regenerating oral epithelium (OE). Laminin g₂ was diffusely detected on the tooth surface and in connective tissues beneath the regenerated OE at 3 and 5 days post-surgery. At 7 days post-surgery, laminin g₂ was intermittently recognizable in the internal basal lamina (IBL) close to tooth facing cells, while laminin g₂, integrin b₄ and integrin a₃ were observed in the IBL and in the external basal lamina (EBL) of the regenerated junctional epithelium (JE) at 14 days post-surgery. 

Conclusion: These results suggest that massive secretion of laminin-5 in the connective tissue may induce epithelial cell migration, and that binding of laminin-5 to integrin a₆b₄ and integrin a₃b₁ in the IBL may provoke cell adhesion and migration of cells tooth facing on the enamel surface of the newly formed JE. (This research was supported by an Oral Health Science Center Grant HRC7 from the Tokyo Dental College, by a "High-Tech Research Center" Project for Private Universities from MEXT of Japan, 2006-2010.)