Protein in Stool Could Be a Marker of Disease Severity in Cystic Fibrosis

The levels of a protein called calprotectin in the stool could not only be a marker of intestinal disease but could also help determine disease severity in cystic fibrosis (CF), according to a study published in the scientific journal Immunobiology.

This marker could therefore be useful to monitor clinical worsening of the disease over time.

In the study titled “Severe disease in Cystic Fibrosis and fecal calprotectin levels,” a team of researchers led by Dr. Salvatore Leonardi of the Department of Clinical and Experimental Medicine at the University of Catania in Italy enrolled 54 CF patients and 50 healthy volunteers between January and December 2015.

Researchers collected stool samples and measured the levels of calprotectin in the stool of all participants.

Calprotectin is a calcium-binding protein that is found in high levels in a type of immune cells called neutrophils. The presence of calprotectin in stool indicates the migration of neutrophils to the intestines. This occurs in case of inflammation.

The team found that in CF patients, the levels of calprotectin were significantly higher than in healthy volunteers. Moreover, the levels of calprotectin were significantly higher in CF patients who were older than 18 years, who had pancreatic insufficiency, were underweight, had an infection in their airways with the pathogenic bacteria Pseudomonas aeruginosa, had CF-related diabetes, had reduced lung function, or had had a high number of pulmonary exacerbations.

“These results suggest that in patients with CF, [stool calprotectin] levels are not only influenced by the CF enteropathy (disease of the intestine) but also by the severity of the genetic disease,” the authors concluded.

Researchers noted that based on the higher levels of calprotectin found in the stool of patients with a severe disease, such as those with P. Aeruginosa airway infection, reduced lung function, pancreatic insufficiency, and underweight status, they suggest that the levels of calprotectin could be a good biomarker to monitor disease severity over time.

Levels of calprotectin in stool are already in use as a clinical biomarker to assess the presence of bowel inflammation. Interestingly, recent studies had suggested that in CF patients there may be a correlation between bowel and lung disease.