Exogenous activation of Wnt/ß-catenin signaling attenuates binge alcohol-induced deficient bone fracture healing.

AIMS: Excessive alcohol consumption is associated with fracture non-union. Canonical Wnt pathway signaling activity regulates normal fracture healing. We previously demonstrated that binge alcohol exposure modulates ß-catenin levels in the fracture callus of mice. Here, we sought to determine whether exogenous enhancement ß-catenin signaling activity could restore normal fracture healing to binge-exposed mice. METHODS: C57BL/6 male mice were exposed to episodic alcohol or saline for 6 total days of alcohol exposure over a 2-week period. Following alcohol exposure, mice were subjected to a stabilized mid-shaft tibia fracture. Beginning 4 days post-injury, mice received daily injections of either lithium chloride or saline subcutaneously. Protein levels of activated, inactivated, and total ß-catenin and GSK-3ß in fracture calluses were measured at post-injury day 9. Biomechanical strength testing and histology of callus tissue was assessed at post fracture day 14. RESULTS: Binge alcohol was associated with decreased callus biomechanical strength, and reduced cartilaginous callus formation. Alcohol decreased levels of callus-associated activated ß-catenin while concomitantly increasing the levels of inactive ß-catenin at post-injury day 9. Alcohol also increased callus associated activated GSK-3ß at post-injury day 9. Lithium chloride (an inhibitor of GSK-3ß) treatment increased activated ß-catenin protein levels, significantly decreased activated GSK-3ß and restored cartilaginous callus formation and endochondral ossification. CONCLUSION: These data link alcohol-impaired fracture healing with deregulation of Canonical Wnt signaling activity in the fracture callus. Exogenous activation of the Wnt pathway using LiCl attenuated the damaging effects of binge alcohol exposure on the fracture healing process by modulating canonical Wnt signaling activity.