Corona-Intestine - Développement d'un modèle biomimétique de l'intestin humain pour étudier l'infection de l'intestin par le SARS-CoV-2 [ Corona-Intestine - Development of a biomimetic model of the human intestine to study SARS-CoV-2 infection of the intestine]

Entry of SARS-CoV-2 is mediated by the Spike S protein, which recognizes the ACE2 cellular receptor, expressed in various tissues: lung, heart and blood vessels, but also in the intestine. Intestinal infections with SARS-CoV-2 have been previously reported (Xiao et al., 2020). We have also been able to observe, along with others, the uptake of S-protein-expressing pseudoviruses (from SARS-CoV-2) in a human colon-type cell line (Hoffmann et al., 2020). However, it is not yet known to what extent the intestine is targeted by the virus (small intestine or colon) and what is the consequence of this infection on the viral spread. Additionally, the effect of SARS-CoV-2 infection on intestinal homeostasis has not been clearly studied. In the intestine, ACE2 is involved in the transport of amino acids that impact the gut microbiota and the inflammatory response (Hashimoto et al., 2012). Since patients with inflammatory syndrome and / or dysbiotic microbiota have a higher risk of developing severe covid19, intestinal infections may play an important role in worsening the disease. Therefore, studying coronavirus infections at the level of the intestinal barrier will provide important information about the disease and the outbreak of COVID-19. However, infection with SARS COV-2 is specific to the human population and the community therefore does not have precise animal models to study the infection in vivo. An alternative approach would be to use a human biomimetic gut using the new organ-on-chip devices that combine tissue engineering and microfluidic technologies. This allows us to reproduce the architecture (in 3D organized in a crypt / villus-like structure) and the mechanical forces observed in the intestine (fluid flow and peristaltic movement) (Bein et al., 2018). We recently developed this technology using Caco-2 cells matured in intestines on chips from the company Emulate. This allowed us to observe how essential the 3D topology and mechanical stimulation of the epithelial monolayer of the intestine was for the invasion of the entero-invasive pathogen Shigella (Grassart et al., 2019). In addition, we have successfully implemented the generation and expansion of intestinal organoids (Nigro et al., 2014; Nigro et al., 2019). Indeed, from colonic organoids, obtained from human colonic resections, we were able to generate polarized monolayers of primary human colonic cells (on Transwell), thus reproducing the colonic barrier with all the panoply of colonic cells ( colonocytes, cross-sectional cells, enteroendocrine cells). We propose to combine our two approaches to develop a biomimetic human intestine to study coronavirus infection. In this project, we will develop a model of human gut using primary human cells (organoid-derived) from colon and small intestine tissues in addition to organ-on-chip technology to reproduce the full feature of the barrier of the small intestine and the colon (diversity of cells, 3D topology, mechanical stimulation). This will allow us to study the adhesion, fusion, entry and replication of SARS-CoV-2 from ileum to colon and the downstream impact on intestinal homeostasis. This project will therefore allow us to determine whether the intestine is a reservoir for SARS-CoV-2 and its impact on intestinal homeostasis. Once our method and model are validated, it will be available to the scientific community and clinical studies could be performed using tissue from patients with covid19 to enable personalized medicine and drug testing. In addition to the urgency of the study of covid19, our project will also be useful for studying intestinal diseases, in particular during enteric infections.