Group B Streptococcus crosses human epithelial cells by a paracellular route

Area of Science:

• Microbiology
• Pathogenesis
• Epithelial Biology

Background:

• Group B Streptococcus (GBS) colonization is crucial for infection pathogenesis.
• Mechanisms of GBS translocation across epithelial barriers remain poorly understood.

Purpose of the Study:

• To investigate the strategies employed by GBS to translocate through the epithelial barrier.
• To elucidate the role of bacterial factors and epithelial junctions in GBS invasion.

Main Methods:

• Utilized differentiated epithelial cells on transwell inserts as an in vitro epithelial barrier model.
• Employed transmission electron microscopy to visualize bacterial interaction with epithelial cells.
• Assessed bacterial adherence, invasion, and translocation across the monolayer.

Main Results:

• GBS translocation occurred without significant decrease in transepithelial resistance.
• Acapsular GBS showed increased adherence and invasion, but translocation was capsule-independent.
• GBS translocated via a paracellular mechanism, involving active, transient opening of intercellular junctions.
• GBS localized with junctional proteins, indicating interaction with cell adhesion complexes.

Conclusions:

• GBS actively disrupts intercellular junctions to facilitate paracellular translocation across the epithelial barrier.
• The bacterial capsule does not influence the translocation efficiency across the epithelial monolayer.
• Understanding these translocation mechanisms is key to preventing GBS infections.