Figure 1: Components of intestinal innate immune system. (a) Lines of intestinal innate defense: mucus layer (outer and inner mucus layer), epithelium and lamina propria with different cells. (b) Representation of a surface-anchored mucin protein. (c) Representation of an oligomeric secreted mucin protein. (d) Cellular distribution of TLRs and NOD receptors and their ligands in an innate immune cell.