Liver sinusoidal endothelial cells contribute to the uptake and degradation of entero bacterial viruses

Cristina I Øie,Tanji Yasunori,Balpreet S Ahluwalia,Peter A Mccourt,Karen K Sørensen,Bård Smedsrød,Gianina Dumitriu,Deanna L Wolfson

doi:10.1038/s41598-020-57652-0

Abstract

The liver is constantly exposed to dietary antigens, viruses, and bacterial products with inflammatory potential. For decades cellular uptake of virus has been studied in connection with infection, while the few studies designed to look into clearance mechanisms focused mainly on the role of macrophages. In recent years, attention has been directed towards the liver sinusoidal endothelial cells (LSECs), which play a central role in liver innate immunity by their ability to scavenge pathogen- and damage-associated molecular patterns. Every day our bodies are exposed to billions of gut-derived pathogens which must be efficiently removed from the circulation to prevent inflammatory and/or immune reactions in other vascular beds. Here, we have used GFP-labelled Enterobacteria phage T4 (GFP-T4-phage) as a model virus to study the viral scavenging function and metabolism in LSECs. The uptake of GFP-T4-phages was followed in real-time using deconvolution microscopy, and LSEC identity confirmed by visualization of fenestrae using structured illumination microscopy. By combining these imaging modalities with quantitative uptake and inhibition studies of radiolabelled GFP-T4-phages, we demonstrate that the bacteriophages are effectively degraded in the lysosomal compartment. Due to their high ability to take up and degrade circulating bacteriophages the LSECs may act as a primary anti-viral defence mechanism.

Highlights

The liver is constantly exposed to dietary antigens, viruses, and bacterial products with inflammatory potential
We investigated the uptake of bacteriophages by primary cultures of rat liver sinusoidal endothelial cells (LSECs), focusing on the clearance ability of the LSECs rather than viral infection
Isolated rat LSECs in culture were pulsed for 15 min with a low concentration of Alexa Fluor-647-formaldehyde treated bovine serum albumin (AF647-Formaldehyde-treated bovine serum albumin (FSA)) (5 μg/ml), non-attached ligand washed off, and the cells further incubated for another 1.5 h to functionally mark the late endosomal and lysosomal compartments[24]

Summary

Introduction

The liver is constantly exposed to dietary antigens, viruses, and bacterial products with inflammatory potential. We studied the uptake and degradation of T4-phages in primary cultures of freshly isolated rat LSECs, demonstrating the transport of the particles to the lysosomes in real-time using deconvolution microscopy.

Results

Conclusion