Adhesion Molecule Deficiencies Increase Porphyromonas gingivalis -Induced Alveolar Bone Loss in Mice

Abstract

ABSTRACT Alveolar bone resorption can be induced in specific-pathogen-free mice by oral infection with Porphyromonas gingivalis (P. J. Baker, R. T. Evans, and D. C. Roopenian, Arch. Oral Biol. 39:1035–1040, 1994). Here we used a mouse strain, C57BL/6J, which is relatively resistant to P. gingivalis -induced bone loss to examine whether partial or complete deletion of various adhesion molecules would increase susceptibility. Complete deletion of P-selectin or nearly complete lack of expression of intercellular adhesion molecule 1 (ICAM-1) led to increased susceptibility to bone resorption after oral infection, while a hypomorphic defect in β 2 -integrins did not. Both the total amount of bone lost and the number of sites at which there was significant loss were increased in mice deficient in either ICAM-1 or P-selectin. Each of the three adhesion molecule deficiencies was sufficient to decrease P. gingivalis -specific serum immunoglobulin G responses, but lower antibody titers did not lead to increased bone loss in partially β 2 -integrin-deficient mice. In conclusion, P-selectin and ICAM-1 deficiencies increase susceptibility to and severity of alveolar bone loss after P. gingivalis infection. This finding underscores the importance of innate immunity in protection against P. gingivalis -induced alveolar bone resorption.