Relationship between intestinal permeability and calprotectin concentration in gut lavage fluid

Calprotectin is released from neutrophils and monocytes, and increased calprotectin levels in stool may serve as a marker of intestinal inflammation. Intestinal permeability is increased in inflammatory bowel diseases, especially in Crohn disease. We studied the relationship between intestinal permeability and calprotectin concentration in intestinal lavage fluid in patients with known or suspected inflammatory bowel disease (IBD).

Thirty-eight patients were examined; 17 had Crohn disease; 3, ulcerative colitis; and 18, irritable bowel syndrome. Intestinal lavage was performed by means of a nasojejunal tube positioned by gastroduodenoscopy. By means of a peristaltic pump 2 l isotonic polyethylene glycol solution (MW, 3350) containing 50 microCi 51Cr-labelled ethylenediaminetetraacetic acid (EDTA) were administered through the tube over a period of 40 min. The first clear fluid passed per rectum was collected and analysed for calprotectin levels with an enzyme-linked immunosorbent assay method. Urine was collected for 5 h and analysed for gamma radioactivity. 51Cr-EDTA excretion in urine was expressed as percentage of dose administered (that is, intestinal permeability).

Both intestinal permeability and calprotectin concentration were significantly higher in patients with IBD than in patients with functional conditions. In Crohn disease the values depended on disease activity but not on whether the disease was located in the small or in the large bowel. There was a highly significant correlation between calprotectin concentration in gut lavage fluid and intestinal permeability (r=0.79, P<0.0001).

The significant correlation between calprotectin concentration in gut lavage fluid and intestinal permeability supports the view that increased intestinal permeability in IBD might, at least in part, be a consequence of increased transepithelial migration of neutrophils.