Lipopolysaccharide structure impacts the entry kinetics of bacterial outer membrane vesicles into host cells

• Published in: PLoS pathogens Vol. 13; no. 11; p. e1006760
• Main Authors: O'Donoghue, Eloise J, Sirisaengtaksin, Natalie, Browning, Douglas F, Bielska, Ewa, Hadis, Mohammed, Fernandez-Trillo, Francisco, Alderwick, Luke, Jabbari, Sara, Krachler, Anne Marie
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.11.2017; Public Library of Science (PLoS)
• Subjects: Antigens; Bacteria; Bacterial infections; Bacterial vesicles; Biology and Life Sciences; Cell interactions; Cell Wall - chemistry; Cell Wall - metabolism; Cell walls; Clathrin; Coding; E coli; Endocytosis; Escherichia coli; Funding; Genetic code; Gram-negative bacteria; Gram-Negative Bacteria - chemistry; Gram-Negative Bacteria - metabolism; Gram-Negative Bacterial Infections - metabolism; Gram-Negative Bacterial Infections - microbiology; Host-Pathogen Interactions; Humans; Infections; Kinetics; Lipopolysaccharides; Lipopolysaccharides - chemistry; Lipopolysaccharides - metabolism; Medicine and Health Sciences; Membrane vesicles; Methods; O antigen; Pathogenesis; Priming; Research and Analysis Methods; Salmonella; Toxins; Transport Vesicles - metabolism; Transport Vesicles - microbiology; Vesicles; Virulence; Virulence factors; Virulence Factors - metabolism
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1006760

Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections.