For host transcripts, calprotectin is a well-characterized biomarker routinely used in clinical practice to assess gut mucosal inflammation19; CXCL5 and IL-8 are both elevated in intestinal biopsies from patients with IBD44,45; additionally, OSM levels in intestinal tissues have recently been strongly correlated with a lack of response to anti-TNF agents20, a widely used class of medications to treat IBD. This evidence concerns the gene CXCL5 and inflammatory bowel disease.