Modulation of the E-cadherin/β-catenin signaling pathway in human cells infected in vitro with Coxiella burnetii

High concentration of soluble E-cadherin (E-cad) was previously found in sera from Q fever patients. Here, BeWo cells which express a high concentration of E-cad were used as an in vitro model to investigate the expression and function of E-cad in response to infection by Coxiella burnetii, the etiological agent of Q fever. Infection of BeWo cells with C. burnetii leads to a decrease in the number of BeWo cells expressing E-cad at their membrane. A shedding of soluble E-cad was associated with the post-infection decrease of membrane-bound E-cad. The modulation of E-cad expression requires bacterial viability and was not found with heat-inactivated C. burnetii. Moreover, the intracytoplasmic cell concentration of β-catenin (β-cat), a ligand of E-cad, was reduced after bacterial infection, suggesting that the bacterium induces modulation of the E-cad/β-cat signaling pathway and CDH1 and CTNNB1 genes transcription. Finally, several genes operating the canonical Wnt-Frizzled/β-cat pathway were overexpressed in cells infected with C. burnetii. This was particularly evident with the highly virulent strain of C. burnetii, Guiana. Our data demonstrate that infection of BeWo cells by live C. burnetii modulates the E-cad/β-cat signaling pathway.