IL17A and Crohn disease: Stalhofer J et al. also showed a synergetic effect of IL-17A with IL-22 and TNF-α for inducing Lcn2 in human colonic epithelial cell lines, and reported that patients with Crohn’s disease carrying IBD risk-increasing IL23R alleles who might have impaired T helper 17 cells-associated immune responses showed lower serum Lcn2 concentration than those not carrying26.