Bacterial-host adhesion dominated by collagen subtypes remodeled by osmotic pressures

Environmental osmolarity plays a crucial role in regulating functions and behaviors of both host cells and pathogens. However, it remains unclear whether and how environmental osmotic stimuli modulate bacterial-host interfacial adhesion. Using single-cell force spectroscopy, we revealed that the interfacial adhesion force depended in a nonlinear manner on osmotic prestimulation of host cells but not bacteria. Quantitatively, the adhesion force increased dramatically from 25.98 nN under an isotonic condition to 112.45 or 93.10 nN after the host cells were treated with the hypotonic or hypertonic solution. There was a strong correlation between the adhesion forces and the number of host cells harboring adherent/internalized bacteria. We further uncovered that osmoregulated overexpression of collagen XV and II was responsible for the increase in the interfacial adhesion under the hypotonic and hypertonic conditions, respectively. The work provides a new idea for developing host-directed antibacterial strategies related to interfacial adhesion from a mechanobiological perspective.