Intestinal IL-1β Plays a Role in Protecting against SARS-CoV-2 Infection.

The intestine is constantly balancing the maintenance of a homeostatic microbiome and the protection of the host against pathogens such as viruses. Many cytokines mediate protective inflammatory responses in the intestine, among them IL-1β. IL-1β is a proinflammatory cytokine typically activated upon specific danger signals sensed by the inflammasome. SARS-CoV-2 is capable of infecting multiple organs, including the intestinal tract. Severe cases of COVID-19 were shown to be associated with a dysregulated immune response, and blocking of proinflammatory pathways was demonstrated to improve patient survival. Indeed, anakinra, an Ab against the receptor of IL-1β, has recently been approved to treat patients with severe COVID-19. However, the role of IL-1β during intestinal SARS-CoV-2 infection has not yet been investigated. Here, we analyzed postmortem intestinal and blood samples from patients who died of COVID-19. We demonstrated that high levels of intestinal IL-1β were associated with longer survival time and lower intestinal SARS-CoV-2 RNA loads. Concurrently, type I IFN expression positively correlated with IL-1β levels in the intestine. Using human intestinal organoids, we showed that autocrine IL-1β sustains RNA expression of IFN type I by the intestinal epithelial layer. These results outline a previously unrecognized key role of intestinal IL-1β during SARS-CoV-2 infection.
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