Bacteriophage uptake by Eukaryotic cell layers represents a major sink for phages during therapy

Abstract

For over 100 years, bacteriophages have been known as viruses that infect bacteria. Yet it is becoming increasingly apparent that bacteriophages, or phages for short, have tropisms outside their bacterial hosts. During phage therapy, high doses of phages are directly administered and disseminated throughout the body, facilitating broad interactions with eukaryotic cells. Using live cell imaging across a range of cell lines we demonstrate that cell type plays a major role in phage internalisation and that smaller phages (< 100 nm) are internalised at higher rates. Uptake rates were validated under physiological shear stress conditions using a microfluidic device that mimics the shear stress to which endothelial cells are exposed to in the human body. Phages were found to rapidly adhere to eukaryotic cell layers, with adherent phages being subsequently internalised by macropinocytosis and functional phages accumulating and stably persisting intracellularly. Finally, we incorporate these results into an established pharmacokinetic model demonstrating the potential impact of phage accumulation by these cell layers, which represents a major sink for circulating phages in the body. Understanding these interactions will have important implications on innate immune responses, phage pharmacokinetics, and the efficacy of phage therapy.

Bacteriophage Interactions With Epithelial Cells: Therapeutic Implications

“…Bichet et al ( 2020 ) examined the rate of T4 phage uptake by different cell types. A549 lung epithelial cells showed the highest accumulation of phages, while endothelial cell types showed intermediate levels.…”

“…It is known that lung alveolar epithelial cells are critical in protection of the respiratory tract against pathogens (Chuquimia et al, 2013 ). The coronavirus propagates within those cells inducing their apoptosis and death (Mason, 2020 ) As mentioned above, phages are capable of entering those cells and may inhibit their apoptosis (Trend et al, 2017 ; Bichet et al, 2020 ). Therefore, one could hypothesize that phages may protect lung alveolar cells against coronavirus-induced injury.…”

Sepsis, Phages, and COVID-19

“…This historical data has been supported by new findings indicating a protective action of the T4 phage on human lung epithelial cells infected with human adenovirus (Adv); furthermore, adsorption of Adv to human lung and kidney epithelial cells as well as viral replication was also inhibited [37]. New data suggest that cell layers of the body may be the major sink for administered phages; interestingly, lung epithelial cells show the highest accumulation of phages [38]. Moreover, the expression of Adv genes and synthesis of Adv DNA may also be downregulated by T4 and staphylococcal phages [39].…”

Recent Advancements in Receptor Layer Engineering for Applications in SPR-Based Immunodiagnostics

“…Bacteriophages, also known as phages, are viruses that infect bacteria and the most abundant form of life on the planet [ 129 ]. They are extremely stable, and it is very easy to modify them, both genetically and chemically [ 130 ].…”