Published online Aug 21, 2017. doi: 10.3748/wjg.v23.i31.5669
Peer-review started: May 19, 2017
First decision: June 22, 2017
Revised: June 30, 2017
Accepted: July 12, 2017
Article in press: July 12, 2017
Published online: August 21, 2017
To evaluate the measurement of zonulin level and antibodies of zonulin and other tight junction proteins in the blood of controls and celiac disease patients.
This study was conducted to assess the variability or stability of zonulin levels vs IgA and IgG antibodies against zonulin in blood samples from 18 controls at 0, 6, 24 and 30 h after blood draw. We also measured zonulin level as well as zonulin, occludin, vinculin, aquaporin 4 and glial fibrillary acidic protein antibodies in the sera of 30 patients with celiac disease and 30 controls using enzyme-linked immunosorbent assay methodology.
The serum zonulin level in 6 out of 18 subjects was low or < 2.8 ng/mL and was very close to the detection limit of the assay. The other 12 subjects had zonulin levels of > 2.8 ng/mL and showed significant fluctuation from sample to sample. Comparatively, zonulin antibody measured in all samples was highly stable and reproducible from sample to sample. Celiac disease patients showed zonulin levels with a mean of 8.5 ng/mL compared to 3.7 ng/mL in controls (P < 0.0001). Elevation of zonulin level at 2SD above the mean was demonstrated in 37% of celiac disease patients, while antibodies against zonulin, occludin and other tight junction proteins was detected in up to 86% of patients with celiac disease.
Due to its fluctuation, a single measurement of zonulin level is not recommended for assessment of intestinal barrier integrity. Measurement of IgG and IgA antibodies against zonulin, occludin, and other tight junction proteins is proposed for the evaluation of the loss of intestinal barrier integrity.
Core tip: We studied possible variability in zonulin levels vs measuring antibodies against zonulin and other tight junction proteins in blood. We found that fluctuations in zonulin level from hour-to-hour and day-to-day were too great to recommend it for assessing intestinal permeability. Measurement of IgG and IgA antibodies against tight junction proteins in controls and in celiac disease patients proved to be very stable and reproducible, and we recommend this method for such an assessment in future studies.