Figure 3.

Comparing the gut environment in physiological and inflammatory conditions. Key features of a healthy normal gut are shown (left), with a thick mucus layer and intactgut epithelium preventing the entry of gut microbiota to the underlying lamina propria. Antimicrobial peptides are secreted by paneth cells into the mucus layer and gut lumen, which regulates the growth of commensals and pathogens. Disruption of these factors leads to gut inflammation (right). The mucus layer is much thinner allowing the association ofbacteria to the epithelium. Gut epithelium barrier function is impaired by the reducedexpression of tight junctions, allowing the translocation of bacteria to the lamina propria. This drives inflammation and the increased infiltration of immune cells compared tophysiological conditions. Reduced expression of antimicrobial peptides occurs due to theimpaired function of Nucleotide-binding oligomerization domain-containing protein 2(NOD2). Reduced antimicrobial peptide secretion leads to bacterial overgrowth in the gutlumen. (Figure created in BioRender).