PDPN and inflammatory bowel disease: This module contained key myeloid and stromal markers genes (CD14 and PDPN), proinflammatory cytokines (including OSM, IL1B and IL6) and fibroblast activation protein (online supplemental figure 8B) in keeping with the emerging concept of a pathogenic myeloid-stromal cell circuit in IBD.18 24 Intriguingly, however, we found that IL23A expression was most strongly correlated with two modules of ‘immune cell differentiation’ (r=0.7) and ‘lymphocyte differentiation’ (r=0.71) genes (online supplemental figure 8A).