Gelatinase regulates the egress of intracellular replicating populations during Enterococcus faecalis infection

Abstract

Enterococcus faecalis is a common opportunistic pathogen, frequently isolated from chronic wounds, yet the mechanisms underlying its virulence and persistence in this niche remain incompletely understood. We previously showed that a subpopulation of E. faecalis can survive intracellularly for several days during murine wound infection and can replicate within macrophages, revealing an unexpected intracellular phase for this traditionally extracellular bacterium. Here, we identify the secreted metalloprotease gelatinase (GelE) and its regulator, the Fsr quorum sensing system, as key modulators of E. faecalis intracellular survival and replication. Mechanistically, Fsr quorum sensing is induced during intracellular replication, promoting GelE-dependent host cell lysis and bacterial egress. In the absence of active GelE, E. faecalis accumulates as large intracellular clusters, a phenotype observed consistently across GelE deficient wound isolates. In a mouse wound model, GelE deficient E. faecalis similarly exhibited higher intracellular numbers within wound infection-associated host cells. Together, our study uncovers GelE as a central effector that orchestrates the transition between intracellular and extracellular lifestyles of E. faecalis, providing a possible explanation for its persistence in chronic wound infection.