Biomarkers to Monitor Gluten-Free Diet Compliance in Celiac Patients

Abstract

Gluten-free diet (GFD) is the only treatment for celiac disease (CD). There is a general consensus that strict GFD adherence in CD patients leads to full clinical and histological remission accompanied by improvement in quality of life and reduced long-term complications. Despite the importance of monitoring the GFD, there are no clear guidelines for assessing the outcome or for exploring its adherence. Available methods are insufficiently accurate to identify occasional gluten exposure that may cause intestinal mucosal damage. Serological tests are highly sensitive and specific for diagnosis, but do not predict recovery and are not useful for follow-up. The use of serial endoscopies, it is invasive and impractical for frequent monitoring, and dietary interview can be subjective. Therefore, the detection of gluten immunogenic peptides (GIP) in feces and urine have been proposed as new non-invasive biomarkers to detect gluten intake and verify GFD compliance in CD patients. These simple immunoassays in human samples could overcome some key unresolved scientific and clinical problems in CD management. It is a significant advance that opens up new possibilities for the clinicians to evaluate the CD treatment, GFD compliance, and improvement in the quality of life of CD patients.

Keywords: celiac disease; feces; gluten immunogenic peptides; gluten-free diet; urine.

Figure 1

Percentage distribution of celiac patients by GIP content in feces by age and sex. GIP, gluten immunogenic peptides. GIP positive (>0.30 µg GIP/g feces, black bar), weak positive (0.16–0.30 µg GIP/g feces, grey bar), and negative (<0.16 µg GIP/g feces, white bar).

Figure 2

Presence of GIP in urine of adult CD patients and correlation with their small bowel histology. Severity of mucosal lesion (Marsh I–III) and histological appearance determined by the Marsh scale. GIP negative (white bar), absence of GIP in urine; GIP weak positive (grey bar), visual presence of GIP not quantifiable in urine (>LDT < QL); GIP positive (black bar), presence of GIP visible and quantifiable in urine (>QL). p = 0.0007 (Fisher’s exact test). Values are expressed as the percentage of patients. CD, celiac disease; GIP, gluten immunogenic peptides; LDT, limit of technique detection; QL, quantification limit. Modified according to Moreno et al. [103].