SARS-COV2 in intestinal organoids

Inflammatory bowel disease (IBD) patients are generally at an increased risk for viral diseases. Viral infections of tissue affected by chronic IBD are insufficiently understood, especially in the context of flare-ups; while some studies have confidently shown aggravation of symptoms in large cohorts, others found no association. Although not considered at an increased risk of Coronavirus Disease 2019 (COVID-19), IBD patients suffer more frequent gastrointestinal symptoms during COVID-19 and a worse outcome has been associated with certain IBD medications and disease activity. For this reason, we generated intestinal epithelial organoids from ileum with Crohn’s disease (CD) and colon with ulcerative colitis (UC) together with healthy controls. Each group included five to six patients. Using RNA sequencing we showed that IBD organoids were not more susceptible to infection. The highest viral load two days after infection was in healthy ileum and is correlated to the expression of SARS-CoV-2 entry receptor ACE2 and proteases CTSL/B. Pathway analyses determined an apparently weaker defense reaction in CD organoids to SARS-CoV-2 which could simply be due to the lower viral load compared to the healthy group. In contrast to CD, there was an activation of viral defense in infected UC colon, especially interferon signaling, resembling highly infected healthy ileum. This was not seen in healthy colon and was unexpected since UC and healthy colon did not differ in viral load. In uninfected IBD organoids compared to healthy, there was an already stronger basal expression of genes implicated in viral defense, for example, of viral sensors OAS1 and OASL in CD and interferon regulatory transcription factor IRF7 in UC. Some were further influenced by SARS-CoV-2 infection with notable differences between CD and UC. To conclude, infection with SARS-CoV-2 did not lead to higher viral numbers in IBD organoids providing reassurance for patients in remission. Still, we observed a more pronounced epithelial defense reaction to the virus in UC colon, prompting further investigations on whether this could be the reason for stronger gastrointestinal symptoms of COVID-19 seen in IBD patients or if it could lead to a consequent IBD flare.