Bacterial swimming and accumulation on endothelial cell surfaces

TL;DR

This study investigates how bacteria swim and accumulate on living endothelial cell surfaces, revealing that biological surfaces influence bacterial behavior differently than inorganic ones, with flow enhancing bacterial accumulation.

Contribution

It provides experimental insights into bacterial motility and adhesion on living tissue surfaces, highlighting the dominance of physical effects over biological complexity in bacterial accumulation.

Findings

Bacterial trapping is reduced on cellular surfaces compared to inorganic surfaces.

Two modes of bacterial adhesion identified: tight and loose.

Flow enhances bacterial surface accumulation via bias-swimming.

Abstract

Flagellar-driven locomotion plays a critical role in bacterial attachment and colonization of surfaces, contributing to the risks of contamination and infection. Tremendous attempts to uncover the underlying principles governing bacterial motility near surfaces have relied on idealized assumptions of surrounding inorganic boundaries. However, in the context of living systems, the role of cells from tissues and organs becomes increasingly critical, particularly in bacterial swimming and adhesion, yet it remains poorly understood. Here, we propose using biological surfaces composed of vascular endothelial cells to experimentally investigate bacterial motion and interaction behaviors. Our results reveal that bacterial trapping observed on inorganic surfaces is counteractively manifested with reduced radii of circular motion on cellular surfaces, while with two distinct modes of bacterial adhesion: tight adhesion and loose adhesion. Interestingly, the presence of living cells enhances bacterial surface enrichment, and imposed flow intensifies this accumulation via bias-swimming effect. These results surprisingly indicate that physical effects remain the dominant factor regulating bacterial motility and accumulation at the single-cell layer level in vitro, bridging the gap between simplified hydrodynamic mechanisms and complex biological surfaces, with relevance to biofilm formation and bacterial contamination.