Catestatin regulates the colonic mucus layer in inflammatory bowel disease

BackgroundThe pro-hormone chromogranin A (CgA) and its bioactive cleavage product catestatin (CST) are both associated with inflammatory bowel disease (IBD) and dysregulated barrier functions, but their exact role has remained elusive. Here, we demonstrate that CST regulates the colonic mucus layer. MethodsCST levels were measured in feces of IBD patients. The mucus layer, goblet cells, and immune cell infiltration were analyzed by histology and electron microscopy in colon tissue from IBD patients and mice with selective deletion of the CST-coding region of the CgA gene. ResultsCST levels were elevated in feces of IBD patients compared to healthy controls. The thickness of the mucus layer was increased in non-affected, but not in inflamed, regions of the colon in IBD patients. The thickness of the mucus layer and concomitant mucus production were also increased in the CST-KO mouse. This mucus phenotype in CST-KO mice could be reversed by bone marrow transplantation from wildtype mice. ConclusionsCST produced by bone-marrow derived immune cells reduces production of the mucus layer in the intestine. This might contribute to the reduced mucus layer in inflamed colon regions of IBD patients. Additionally, CST feces levels might be a biomarker for IBD.