Some studies reported suppression of RANKL-mediated osteoclast formation by conditioned media from GFs infected with P. gingivalis or stimulated with Escherichia coli LPS17,18, whereas others suggested a pro-osteoclastogenic role upon infection with P. gingivalis or treatment with subgingival biofilms, attributed to a shift in the RANKL/OPG expression ratio favoring osteoclastogenesis19,21. The gene discussed is TNFSF11; the disease is infection.